In order to rationally evaluate structural characteristic of the rock masses in Gaoyang section of Three Gorges Reservoir and provide guidance for engineering disaster harnessing,the fracture investigation of rock masses was carried out and joints network was simulated.By the field survey of discontinuous of rock mass,a probability model of the geometic parameters of discontinuous,which is accord with the actual situation,was established.The two dimensional joints network was simulated by means of computer simulating technique base on monte-carlo method and direct method,in which some technical improvement was proposed such as calculations of generalized RQDt and line connection rate,based on this the evaluation of geologic engineering characters of rock mass was made more accordant with the real condition.