Abstract: On the basis of aeromagnetic data analysis of Sichuan Basin and the earthquake region on its western margin, the data processing was conducted with inverse method and program of magnetic intensity in the frequency domain, and the horizontal distribution of apparent magnetic intensity in the investigated area is obtained.The inversion result reflects obvious difference between apparent magnetic intensity of the earthquake region on the western margin of the Basin and that of central Sichuan.Analyses show that low apparent rock intensity of magnetization is due to factors such as lithologic characteristics, tetonic stress and temperature.This paper discusses the cause of weak magnetism in the earthquake region on the western margin of the Basin and the seismogenic environment in the light of magnetic intensity distribution and deep tectonic feature.