why the 3ds mesh has transform??

I have read a 3ds format model file .When it is simple ,it draws well,but when it is complex,some mesh draw at an incorrect position,why ??

Maybe because the 3DS file format stores each mesh in local coordinates, along with a transform matrix of some kind, and you don’t load this transform.

Documentation for the .3ds hierarchy tree format is availabe in this classic resource ; just check chunk B010