Abstract:At 19:06 on September 12,2018,an MS5.3 earthquake occurred in Ningqiang county,Hanzhong city,Shaanxi Province. The earthquake depth given by different institutions are somewhat different. Based on the regional velocity model,the focal depth of this earthquake is calculated in this paper in order to confirm the depth result. Firstly,the focal mechanism solution of the earthquake is obtained by inversion by using the CAP method,and then the focal depth is further determined by using the Rayleigh surface wave amplitude spectrum and the error function of the CAP method. The calculation results show that the focal depth of the Ningqiang MS5.3 earthquake obtained by the CAP method is about 12km,while that of the Rayleigh surface wave amplitude spectrum is 13km. Combining with the above two methods,it is finally determined that the focal depth of the Ningqiang MS5.3 earthquake is about 13km,which indicates that this earthquake occurred at the upper crust.