The invention belongs to the technical field of power system operation and provides a power system operation optimization method and a terminal device. The method includes the following steps: according to the power system net load climbing power, the index of power system flexibility is determined. According to the unit cost converted from the power loss of the power system climbing power and theindex of power system flexibility, the conversion cost of the power loss of the power system climbing power is determined; according to the demand response cost of the power system, the power systemrenewable energy electricity abandoning cost and the power system climbing power loss conversion cost, the total operation cost of the power grid is determined; based on the particle swarm optimization algorithm, aiming at the minimum total cost of the operation of the power grid, the power system interrupt load size and the abandoned wind and light amount of the power system are solved; accordingto the power system interrupt load size, the abandoned wind and light amount and the flexibility index, the operation optimization of the power system can be carried out. The flexibility requirementof the power system can be quantitatively analyzed and the power grid scheduling scheme conforming to the actual situation is obtained.