The invention discloses a bridge deformation multi-frequency dynamic analysis method based on a combined differential GNSS and relates to the field of bridge deformation monitoring technologies. According to the method, an orthogonal wavelet fast decomposition algorithm is utilized to process a bridge GNSS monitoring signal, an analysis signal is separated on different bands, and multi-scale analysis is performed on a deformation signal; a high-frequency signal is utilized to analyze wink movement of a bridge under the action of external forces such as wind power, vehicle passage or other seismic disasters, and a de-noised low-frequency signal is utilized to analyze a deformation track of a bridge dynamic deformation body; and last, the analysis result is utilized to further analyze the bridge deformation trend. Therefore, by analyzing the characteristics of different frequencies in the GNSS monitoring signal, a static response and a dynamic response of the bridge can be effectively decomposed, the problem that the reason for bridge deformation caused by a bridge three-dimensional displacement change cannot be judged through an existing bridge monitoring system is solved, subsequent monitoring analysis is effectively guaranteed, and a good guarantee is provided for safety monitoring of the bridge.