With the increasing application of wind power in power systems, the uncertainty of wind power brings new challenges in both reserve capacity decision-making and generation dispatching. By considering the operation security of wind power integrated system, a kind of system operation security index, reserve security reliability, is proposed by combining with the probability density function of forecasting error for wind power. With the objective function being the maximum reserve security reliability and the minimum fuel cost, the economic dispatching model of power grid with wind power is built. In order to improve optimization efficiency, an optimized method that combines interior-point method with priority method is applied to solve the problem of unit commitment. In the end, test cases verify the feasibility and reasonability of proposed model and solution method.