Abstract: With the technical progress of Renewable Energy Resources (RERs) generation and the support from domestic incentive policies, the installation proportion of renewable energy resources has been increased steadily. The integration of renewable energy resources not only shows significant environmental effect, social effect and economic effect, but also brings many challenges to grid planning and economic operation of power grid. Based on system dynamics, from the perspective of changes of cost and benefit of grid enterprises caused by the integration of RERs, the effect of the integration of RERs on economical operation of power grid is studied. Finally, a simulation of effect trend based on empirical data of one province demonstrates the validity of the model proposed in this study.