It is very important to understand the process of earthquake preparation and to carry out earthquake prediction research of the significant abnormal changes which are related to the earthquake. However,no many people have carried out such researches in past. In this paper we analyzed the characteristics of some significant deformation anomalies before Wenchuan earthquake,and found that there are few anomalies near the epicenter before the earthquake,whereas some prominent anomalies are found around the periphery. In order to find the correlation between far field anomalies and earthquake,we proposed a correlation criterion based on a modified statistical-physical model between the precursor duration,epicenter distance and magnitude. A case study of relationship between leveling anomalies along Hongliuxia fault and Wenchuan has been carried out. Finally,we discussed the dynamic meanings of far field deformation precursors.