Based on background noise and tomography methods,in this paper,we investigated the continuous waveform records of 94 fixed seismic stations in the northern segment of the north-south seismic belt from January to September,2013.In doing so,we obtained the velocity structure and evolution of the Rayleigh waves of this area,at different times in the same two-month period before and after the Minxian-Zhangxian M_S6.6 earthquake on July 22,2013.The phase velocity tomography results show that before the earthquake,in May-June,the wave velocity along the Lintan-Tanchang fault zone and its surrounding areas reduced relative to that in March-April.However,after the earthquake,in August-September,the wave velocity along the Lintan-Tanchang fault zone and its surrounding areas was restored by rising to the level of May-June.These results indicate that in the two months before the Minxian-Zhangxian M_S6.6 earthquake,the velocity exhibited low-value anomalies,and the earthquake occurred at the boundary of the low-velocity anomaly region.