This paper lists the address background and instrument observation condition about the borehole strain in Huailai Seismic Station; Analyses the interference in actual observation in the borehole strain by instrument zero drift, air pressure, water level, rainfall and other factors；It studies Borehole strain the different forms of abnormal changes before the earthquake in the district and its adjacent area and carries on the analysis of characteristics.Research shows that, Borehole Strain observation is an effective way in getting abnormal change information about tectonic activity and geophysical research and earthquake prediction.