Friction is introduced into the modal parameter identification of the time varyi ng vibration systems. The modal characteristics of the vibration system are extr acted by using the time varying multivariable Prony method. A time varying multi variable Prony model is established for the multioutput response signals of th e vibration system and the parameters of the model are estimated by means of the recursive least square method. In the simulation，a signal with composite frequ ency is identified. The identified results meet the theoretical values well, whi ch verifies the effectiveness of the presented method. In the example, the motio n equation of the moving mass on the planar twobar manipulator is established, i n which the LuGre friction is considered. The natural frequency of the manipulat or subjected to stickslip friction is identified by using the time varying mult ivariable Prony method. The feasibility of the method is verified by the satisfy ing identification results. 