Using the seismic waveform data recorded by the Capital Circle Digital Seismic Network of China，the Wadati method is applied to calculate velocity ratio in the Capital Circle Region of China during 2002－2014，the spatialtemporal variation of wave velocity ratio is analyzed before moderatestrong earthquake in the Capital Circle Region of China since 2002. We discussed precursory information of moderate-strong earthquake. In order to ensure the precision and stability of the results，we imposed restrictins on the computation condition. The calculating results shows that there was wave velocity ratio anomaly before many earthquakes in the Capital Circle Region. The low wave velocity ratio anomaly area appeared around the focal region and the earthquake location along the margin of this area，and provide a theoretical basis for the area of the earthquake prediction.