Abstract: This paper establishes the 3-D finite element mechanical models and mathematical models about casing deformation，and develops the simulating software of 3-D casing defor-mation, providing the simple and direct method of analyzing casing collapse caused by the underground complex mechanical system. Under non一uniform distribution loads，the simu-lated results of 3-D casing model are consistent with those of 2-D problem of reference(1). In this case. the 2-D problem is only a special example of 3-D problem of casing.This paper makes the simulation analyses about casing under bending，torque,and inside and outside pressures，and provides a significant theoretical guidance for studying the deforma-tion process of casing under complex mechanical system.

Key words: Casing deformation, Load (force), Spatial distribution, Simulation