With the intermittent and randomness of wind power,the power system needs to arrange certain spinning reserve capacity in response to wind power fluctuations,so the optimal allocation of spinning reserve problem is the key point. This paper first analyzes the potential problems of optimal allocation of spinning reserve by the principle of equal proportion in wind power system; then calculate the optimal power flow which aims to minimize the network loss with the original dual interior point method, of which all thermal power’s active power outputs are optimized objects. You can watch the total network loss and the thermal power’s spinning reserve in the optimal power flow calculation results.Finally the IEEE39 system example and the comparison of two methods demonstrate that the principle of equal proportion exists potential problems and it is necessary to calculate the optimal power flow.