Abstract: The stability of a T-S model based fuzzy control system for both the discrete,linear time-invariant object and the nonlinear time-varying object is analyzed with the help of constructing a related virtual equivalent system.The purpose of adopting the virtual equivalent system is to reduce the difficulty of analyzing the stability of the fuzzy control system and to improve the conditions of existing stability criteria.The results indicate that the stability of the fuzzy control system depends on the precision of local models,the effectiveness of fuzzy rules,and the stabilizing characteristic of each local controller.