To improve the regulating range and response speed of variable frequency hydraulic speed-regulating system, a hydraulic speed-regulating scheme combining variable frequency hydraulic pump and constant speed hydraulic pump was proposed. The mathematical model of the system was established, and combined with the allowable speed range of the hydraulic pump, the flow distribution relationship of the two hydraulic pumps was given. Taking the pump-control-motor hydraulic system as an example, a system simulation model based on speed PID control was established to verify its speed-regulation performance. The results show that by using the proposed speed regulation scheme, the motor rotary speed can be controlled continuously and stably, and the flow distribution of hydraulic pump meets the design requirements.