Abstract: The article surveys and analyses the seismogenic structure and geological settings of Ms8.0 Wenchuan strong earthquake.The paper examined the changing course of deformation field from the angle of fault deformation before the earthquake.The conclusions are as follows: The crustal deformation precursor anomaly within the earthquake area of Wenchuan was in its objective existence,and it is quite salient in some partial area;Mobile short leveling observation data indicated the accelerative movement in Longmenshan fault zone before the earthquake;yet with respect to the current deformation data,it still lacks reasonable basis and certainty regarding the forecasting of such strong earthquake.