Abstract: This paper is focused on the analysis of seismic wave velocity,we utilized the single station methods about P and S wave apparent velocities,and V_P/V_S ratio from the near earthquake data between January 1, 2009 and April 20, 2013 recorded by the stations near the 2013 Lushan 7.0 mainshock epicenter(CD2、 MEK、 GZA、 MDS、 HSH、 JJS、 XJI、 DFU、 EMS、 JYA、 YGD). As a result ,we find clear and synchronous low value anomalies in P wave and S wave apparent velocities apperared on these stations(CD2、 MEK、 GZA、 MDS、 HSH、 JJS). These phenomenaare centralized on the southern area of the active Longmanshan fault, and also the different levels of anomalies in Vp/Vs ratio have been showed. It's likely to be a forewarning of the coming great earthquake when the clear and synchronous of the low value anomalies in P wave asn S wave apparent velocities is appearing on several stations.

Key words: Single station V_P/V_S ratio, P and S wave apparent velocities, The 2013 Lushan 7.0 earthquake