The layered crustal model in Gansu region was obtained based on average synthetic curves of traveling time, which presented more than 2000 initial P and S phases of 143 events, the average model para-meters are follows:
In addition it is suggested in this paper that most of the earthquakes used in this paper seemed to cluster at the depth of about 7km, where the boundary of two layers of different types of gvanit exists. Finally, the feasibility of average synthetic method has been discussed.