Abstract: Base on the Shun-zhi topographic map published in 1926,the density distribution of surface water system in Tangshan and Xingtai areas have been studied with GiS method.The original water system pattern have been kept very well in the early topographic map,which is good for abstracting information from the buried tectonic activity.Since GIS method had the advantage of large information and high calculation speed,the density isogram of water system made with this method reflects the seismostructure and its feature of activiey very well.In this paper,the study method and way are briefly introduced,and the primary results in Tangshan and Xingtai areas are given.