In order to improve the execution rate of dispatching plan, this paper proposes a method of auxiliary decision-making of dispatching plan considering static security and transient stability constrains. First of all, the static security and transient stability of the dispatching plans with contingencies are assessed based on AC power flow and time domain simulation. A linear weighted method is used to calculate the units’ comprehensive control performance index of the static security and transient stability to the unsafe dispatching plans. Secondly, according to the key units, whose comprehensive control performance index is large, the nearest front and back related dispatching plans of the unsafe dispatching plans are searched. And the units’ adjustable space is modified considering the unit ramp rate of the relevant dispatching plans. Then, heuristic method based on the control performance index is adopted to solve the auxiliary decision-making problem. Finally, the auxiliary decision-making results are used to update the dispatching plans through iterative and mutual optimization. The effectiveness of the proposed method is verified by cases in Gansu Power Grid. This work is supported by Science and Technology Project of the Headquarter of State Grid Corporation of China (No. SGFJJY00GHJS1800039).