Abstract: From the equivalent model of rockmass with one set of joint in local coordinate system suggested by Goodman et al,through the coordinate transformation the equivalent model of rockmass with multi-set joint in global coordinate system was obtained.Using the Goodman’s joint element model and the derived equivalent model respectively,2D FEM analyses were made for the rockmasses with one and two sets of joint under some condition of loading.Finally a numerical simulation for an opening excavation in a jointed rockmass was carried out by applying the derived equivalent model.It could be seen that the results of test and computation were roughly identical,so the effectiveness of the derived equivalent model was shown.