An important targetof operation mode planning for power grid is tocontrol short-circuit current level so as to guarantee the security of the circuit breaker. Effective measures like circuit opening and bus splitting will enlarge the electrical distance between buses in substations and power plants, in spite of reducing operation reliability of power grid. This paper proposes an optimization model of operation mode planning for power grid. The objective is to minimize the numbers and breaking capacity of opened circuits. The constraints are short-circuit current limits calculated by node-voltage method, network connectivity limits formulated by DC power flow equations, branch power flow constraints and N-1 security constraints. Taking the least number of breaking circuits as target, a power grid operation mode optimization model to control the short-circuit current level is proposed. WARD equivalence is used to narrow the size of the model and improve the calculation efficiency of the optimization model. The model describes a mixed integer linear programming problem, therefore can be solved by linear programming simplex method and branch and bound method. Simulation program written in C++ is applied to instances of IEEE 39-bus system and an actual power grid. The optimized results confirm the correctness of the proposed model and validity of the algorithm.