Time Varying Autoregressive (TVAR) model is a new method for time-frequency analysis,which has high accuracy in instantaneous frequency measurement of simple non-stationary signal.However,it is not applicable to complex signal.In order to make TVAR model also suitable for the measurements of complex signal instantaneous frequency,it is proposed to use Local Mean Decomposition (LMD) together with TVAR model.This method makes the TVAR model greatly expands its scope of application.Least square method and Kalman Smoothing (KS) algorithm are used respectively to solve the signal parameter model,and the instantaneous frequency is obtained.The simulation analysis shows that:Compared with the instantaneous frequency measurement only using TVAR model,the improved method can greatly improve the accuracy.