Based on principal component analysis method，we analyze comprehensively faultcrossing data before and after the Datong earthquake MS6. 1，the Zhangbei earthquake MS6. 2 and the Wen'an earthquake MS5. 1 in the capital region of China，calculated the fault vertical deformation rate，all principal components and the composite indicator W of fault vertical deformation rate that could reflect the overall level of all faults activity． The results indicates that principal component analysis method could capture most of original information and remove the interference information． It is helpful for us to analyze precursor information． Comprehensive index W can reflect the abnormal changes of the precursor data well，and can also reflect the overall level of earthquake-reflecting of a regional precursor observations． Cross-fault flow deformation data in the capital region of China have strong earthquake-reflecting ability on the Datong earthquake MS6. 1，the Zhangbei earthquake MS6. 2 and the Wen'an earthquake MS5. 1， and can better capture the precursory anomalies information of strong earthquake preparation， development and occurrence．