well, if you create a model and set the player pointer to it you can access it by simply using player.x, .y and .z

i put a model on the map with ent_create ("player.mdl", terrain_pos(100,200,300), move_player);
if it is not good,can give me an example

well if terrain_pos is a function which returns a vector there's nothing wrong with it.
if not, just use a vector
ent_create("player.mdl", vector(100, 200, 300), move_player);

then you can either set the player pointer inside the action (move_player) by using player = me; or by creating the player like this:
player = ent_create(...

ok,thank you very much

no problem, if you need further explanations or help, let me know.