Abstract: Coseismic deformation responses of Wenchuan M8.0 earthquake and anomalies from some observations before the earthquake are analyzed with the digital deformation data in Yixian Seismostation.Seismic disturbance and coseismic step of all observation items have some common characteristics,which reflects the the fluctuation and adjustment process of local strain field under the influence of the earthquake.Anomalies of some observation items before the earthquake,which is consistent relatively well with the time of the earthquake,may include some precursory information.