Abstract: The wind speed of typhoon exhibits obvious non-stationary characteristics, which leads to the non-stationary features in the dynamic response of long-span cable-stayed bridges. To investigate the non-stationary characteristics existing in buffeting response of long-span bridges under the action of typhoon, Sutong Bridge is taken as the research object. Based on wavelet transform (WT), the evolutionary power spectral density (EPSD) estimation method is employed to analyze the non-stationary buffeting response of Sutong Bridge during Typhoon Haikui and Damrey. The analytical results show that the vibration energy of the girder in Sutong Bridge is predominated by specific frequencies. Due to the non-stationary features of the typhoons, the buffeting response of the main girder exhibits non-stationary characteristics to some extent as well. The wavelet-based EPSD estimation method is suitable for analyzing the evolutionary characteristics of the measured structural response, and it is a good supplement for the traditional Fourier method in non-stationary analysis. The results can be utilized to validate the reliability of the non-stationary buffeting analysis theory and provide references for the wind-resistant design of long-span cable-stayed bridges.