In order to explore the influence of different rotational acceleration on the transient internal and external flow characteristics of the axial flow pump and improve the performance of the pump, numerical simulations and experiments were used to analyze the variable frequency speed regulation characteristics of the axial flow pump. Taking three-dimensional turbulent numerical simulation as the main research method and CFX as the calculation platform, three variable frequency speed regulation methods were used to conduct transient numerical simulation; keep the acceleration constant, increased and decreased; and obtain the real-time pump performance curve and pressure characteristic curve. Uniform acceleration and deceleration with constant acceleration maintained the stable change and good stability of head and shaft power, and the pressure change was the most stable in the process. The acceleration and deceleration with decreasing acceleration ran most smoothly at high speed, and the frequency conversion effect was the best. At the same time, the transition to steady-state operation was also the most stable. The research in this paper can provide reference for the stable operation of variable frequency speed regulation of the axial flow pump.