Abstract：3D persistence of rock mass is a very important factor that influences the mechanical behaviors of jointed rock mass. Based on the 3D probability distribution model of the discontinuities established through the 3D numerical modeling technique of network，a new conception and solution of 3D persistence of rock mass are put forward on the basis of the potential failure path of jointed rock mass. With the solution of persistence，the most possible failure path in rock mass can be found out. In the process，the theory of genetic algorithm with the characteristics of biological background is adopted to determine the optimized 3D persistence in complicated jointed rock mass. This new method has been used in a practical hydroelectric project，and the result shows that the new method is available for engineering design.
