The generalized demodulation time-frequency analysis approach is a new signal processing method, In this paper,it is introduced and applied to the decomposition of the multi-composition signals whose frequency is time-varying.For the generalized demodulation time-frequency analysis method ,the improvement has been completed and the method by which the multi-component signal can be decomposed is given .The problems of the method of how to get the phase function and how to obtain the ideal time-frequency distribution by the generalized demodulation time-frequency analysis approach used in the single-component signals got from the original signal are analyzed.The simulation experiment results demonstrate that by using this method not only the time domain wave of the single-component signals in the original signal can be obtained but also the same time-frequency distribution can be got, and an effective method is provided for multi-composition signals whose frequency is time-varying.