Photovoltaic (PV) is a crucial power source in future clean power system, which must be included in the system planning. But the correlation between variable PV power and loads is not involved in traditional planning method. This paper proposed a modified probabilistic production simulation (PPS) method considering the joint probability of PV output and load, especially the conditional dependence of them. The new PPS contains three parts of photovoltaic and load correlation characteristics modeling, photovoltaic probability calculation, and verification of production simulation method. Numerical study is finally proceeded, and the results verified the effectiveness and accuracy of the designed algorithm.