which is more complex,chess or xiangqi(chinese chess)?

One could sum it up by stating: Don't compare oranges and apples (both fruits) or football and volleyball (both played with a ball). Or XiangQi, Shogi, Chess, Backgammon etc.

All board games, but sooooo different.

Well actually, there are these things in chess too. They're called endgame studies; there's a large body of extremely difficult work out there. I'll just give one example below; white to play and win. (Pal Benko, 1989.) You pick white and you'll likely end up drawing; you pick black and the master can beat you.

1. Kc8 Ke7 2. Kc7 Kf8 3. Ng6+ hxg6 4.Kd7 Kf7 5.Kd6 etc.

Correct; the harder-to-see critical line is 1. Kc8 Ke7 2. Kc7 Kf8 3. Ng6+ Kf7 and now 4. ___! is the only winning move.

(Although I personally find xiangqi endgame studies much much harder to calculate out, that's probably because I suck at it. Then again, winning a rook vs all advisors and elephants （单车对士象全） endgame from one of the won starting positions is HARD.)

Nf4

Yep. Congratulations, you can now hustle people with this position! :P (Well, that's why you're a master.)

Well, let's compare(as far as I know, though I rarely have played it):-

Xiangqi:-

1. No pawn structures
2. King/General can move only in castle
3. There is a river in between which affects plans
4. Pieces are small with text/drawing(there is western xiangqi) written on them.
5. Faster game
6. Xiangqi strategy is similar to war strategy. More realistic game.
7. Open Gameplay

Chess:-

1. Different types of pawn structures due to interlocking.
2. King can go anywhere on the board and can help in mate
3. Pawn Structures and other positional and strategical factors affect plans.
4. Pieces are in 3D shapes
5. Slower game
6. The factors of chess strategy rarely relate to anything realistic.
7. Can be open or closed due to interlocking pawns.

Bonus: Atomic chess:-

1. Pawn Structures are rare, but can be formed.
2. King is needed to be protected(more than any game), can not take pieces.
3. More tactical than chess, positional and strategical factors come rarely in consideration.
4. Similar pieces to chess.
5. Faster game
6. More realistic and selfish game
7. Mostly open due to blasts.

Bonus: Antichess:-

1. Interlocking not possible
2. King is not protected
3. Giving away all pieces, tactical
4. Similar to chess
5. Faster game
6. More realistic
7. Can not be closed

Bonus: Shogi:-

1. No pawn structures
2. King can go anywhere and help in mate
3. Movements of pieces like lancer and pawns, strange promotion affects strategy
4. Similar to Xiangqi. Pieces taken can be used.
5. Faster game.
6. Similar to chess
7. Mostly open

2nd Final Bonus: Take all

1. Pawn structures to to interlocking
2. King is a middlegame piece, he needs not be protected
3. Similar to chess
4. Similar to chess
5. Slower game
6. Similar to chess
7. Similar to chess

Final Bonus: Chaturanga:-

1. Pawn structures are formed
2. King should be protected and is 2nd strongest piece(after rook)
3. Pawns and promotion target squares affect strategy
4. Similar to chess
5. Slower game
6. Similar to chess
7. Can be any. Closed good for minor pieces and open for rooks.

Hope that can help to consider most famous variants.

Don't need that position to hustle people. :-)

There was a game combining most board games like chess, backgammon etc. Has anyone tried it out?

You said they are different. Any two different things can be compared.

The statement is ambiguous, but more near false than true.

Chess has 2^155 legal positions, about 10^47. Xiangqi has about 10^48.

I refer you to previous posts. Nobody seems to take into account that in chess a pawn can promote to any piece. Let say I promote all 16 pawns to  knights for instance. Now you've got 20 knights on the board. Did you account for all the positions that could arise from that?

And that's just 1 example from a sheer infinite number of extra possibilities. So everybody stop trying to convince me XiangQi has more possible positions. It's just complete nonsense. (no insult intended)

Of course 2 different things can be compared. But that doesn't mean it makes sense to actually do it.

Remellion, I disappointed you never see a xiangqi book on these problems that have difficult middle position and if you survive the middlegame, they arrive in an endgame and the result is a draw, these positions are very popular among the Chinese. These position start in the middle-game and normally one side looks totally lost but it is complete draw and you have to be master strength in these difficult position. A xiangqi master makes his living on these position, player will pick the side that seem like winning and they normally lose. I played against Taiwanese master, I was able to go into the endgame but lost, these endgame you have to be accurate to draw them. There nothing like this in chess; yes, there is endgames problem, but normally one side is winning or drawing.

If you are able to draw or win against these extremely difficult position, you are properly master strength in xiangqi.

I have seen those positions. I have 3-4 xiangqi books from China and Taiwan, and they are really difficult. (Some are problem books, some are "best games" collections of complex middlegames.) I totally agree those are difficult, I was just pointing out that chess has such positions too, where you have to be extremely accurate to win/draw.

There are many Vietnamese and Chinese to reach 2700 level; I cannot think of one Japanese who was born in Japan and raise there,and he is 2700 level player and also plays Shogi. Many the Vienamese and Chinese have played xiangqi and are strong grandmasters, xiangqi help them to become better player because of xiangqi they are stronger player.

I've played both, and I find chess to be more 'complicated' in the sense of the number of positions that can be easily generated by natural moves....but Xianqi is much harder to get any stability out of. For example, rather than playing an opening phase where you develop your pieces and trade off pawns to create a middlegame structure, the xianqui board starts out open with your pawns advanced and your elephants already guarding key spots on the grid, so the battle lines are drawn immediately.

so, in chess, you have to draw the lines before you begin - meaning that there are more 'shapes' for the game to take. But in Xianqui it's tactics, tactics, tactics from the first move - heavy pieces blasting down every file. 

It is based on concrete calculations by big mathematicians. It contains all legal positions, whatever pawns promote to. There is the Shannon Number of 10^55 which contains illegal positions as well.But still, if you haveany doubt, you can check the calculation used for it. It was available at wikipedia last time I checked.

I find chess more complex, simply due to the fact it is easier to get access to good learning resources. Hence, I can play the game to a higher standard. I dont know whether this is a factor at the higher echelons of the game.

I play Xiangqi.  Elephants aren't that important.  I know a guy who sacrifices his elephants for a pawn majority on the right hand side of the board.  He is so strong, the flying general move never works against him.

My brother and I have taken to remarking "the elephant is relevant!" every time it actually makes a difference on the board (not often), but it still guards your center from invasion, and that's SOMETHING.