Abstract: This article introduces briefly a survey of the establishment of the observation networks; introduces in detail the abundant information contained in the observation of underground water for warning indications of earthquakes. Expounds the theory of underground water microbehaviour and results of experiment; inquires into the abnormal phenomena of underground water behaviour before,during and after some earthquakes,amphasizes that there will be broad prospects for developing and making use of the information contained in underground water behaviour. It is not only of service to earthquake prediction,but also has many uses in geophysics,hydrogeology,new tectonics research and other fields for service to the national economy.