Abstract：There are five abnormity types of component-type borehole strain in Xinjiang，among which the more important is the stepping change type. The relation is systematically studied between the statistical character of anormality of steping change and the earthquake in Xinjiang. It is shown that the anomality of steping change is of short-impending priority. The abnormality with duration less than 90 days is more than 97% of the recorded data. After three months of anomality appearance，the possibility for earthqake to occur is 55%. The magnitude of strain steping change is between 10－6 and 10－4，which consists of elastic deformation and plastic one，and plastic deformation is the main deformation taking 77% of the recorded steping change anormality. The mirror effect of steping change anormality on earthquake is quite good with mirror effect rate of 85%.
