Metal bellows are widely used in mechanical sealing system.The bellows stiffness is the main performance parameter of the metal bellows design.A method for modelling metal bellows by using the Matrix27 stiffness element of ANSYS software instead of shell elements was presented.Compared with the shell elements model,the model size was largely reduced and the calculating efficiency was greatly enhanced.Based on the established simplified finite element model,the axial and torsional stiffness of the metal bellows were analyzed for different samples.The stiffness results were compared with those from the shell elements model and the engineering practical experience formula from EJMA standard.The experimental results from other investigators have also been used for verification.The agreement was excellent.This simplified model is especially advantageous when the bellows is only a part of the whole system.For example,it is valuable to the structural optimization of different types of bellows with respect to overall design parameters of the system,and can effectively improve the efficiency of finite element modeling and analysis.