The anisotropy of magnetic susceptibility (AMS) has been widely used in many fields of the earth science in recent years. In this paper the authors discuss the recent progress in the applications of AMS to these fields, especially in the analysis of structural deformation of rocks. Though the method is very useful, there are many restrictions because of the influence of many factors. In order to use the method correctly, we should pay attention to the prerequisites of the method and do some work to improve it, which will do much good to the applications of AMS to earth science.