Abstract: To make full use of observation data,get rid of interference factors, we build a state space model to extract the hydrology abnormal that relevant to the earthquake.This method can decompose observed groundwater level into five components: atmospheric pressure,tidal,precipitation responses,observation noise,and residual water level.Using state space analysis method,we could obtain the water lever data in the Non-tectonic stress affects,and then,find the law of earthquake evolution through analysis the relations between the trend of the new water lever data and the earthquake activity.