Abstract: Based on the "network ing method" in fuzzy cluster analysis, the fuzzy analysis of the seismicity pattern before Tangshan earthquake has been pro cessed. First, by making the relative intensity betvreea two evtens, we obtat he earthquakes which are included in the Tangshan "earthquake cluster". According to spatial and temporal distribution characteristics of these shocks we may conduct the parmern recognition and analysis for tge seismicity before this stfonglevent. Secondly, we also investigate the relation between Tan gshan earthquake and Xingtai and Bohai earthquakes and discuss the overlap, migration and development of the strong earthquake genesis region from its patial aad temporal variation characteristics of the "earthuqake cluster". It was found that the direction of ther migration and devel opment is about in correspondence with the structure trend. Finally, the results and their application are simply discussed.