Abstract: The Wenchuan earthquake caused tremendous losses of life and property. The relationship between earthquake intensity and fault structure is analyzed in view of geologic abnormal theory. Based on 1∶500000 digital geologic map and Wenchuan earthquake geologic research, this article engaged in geologic abnormal quantitative analysis with GIS technique. It pointed out that earthquake disaster area mainly controlled by regional deep faults. Then earthquake activity which is closely related to destructive power of earthquakes is discussed. The authors obtain hard-hit areas according to the results. Finally we explained why the damage in the northern region is lighter than that in south. Through this approach, the seriousness of the earthquake disaster areas can be determined quickly for future earthquake to guide the disaster relief work.