Abstract: The high-rate GNSS data recorded by some stations during the 2008 Wenchuan M_S8.0 earthquake was used in this paper to identify the arrive time of P-wave and S-wave in 1 Hzhigh-rate GNSS. Coseismic signals are decomposed in two-dimensional time-frequency domain using generalized S transform. The adjustment factors λ_a＝1.05, p＝1.05 is used to identify the arrival times of P-wave and S-wave, which could get a better result. The S transform is effec-tive and feasible in the high-rate GNSS seismic phase recognition.