A new type of two-level digital flow valve was designed for the defect of small and discontinuous flow of high-speed on-off valve. The pilot stage is a motor-driven high-speed on-off rotary valve, and the main stage is a three-position four-way spool valve. The high-speed on-off rotary valve has a high opening and closing frequency, which can significantly reduce the flow fluctuation of the main valve. Based on the structure and working principle of the two-stage valve, a mathematical model and a flow fluctuation model were established. The dynamic simulation model of the two-stage digital flow valve was established with the AMESim software, and the dynamic displacement characteristics and dynamic flow characteristics of the main valve were simulated and calculated. The influence of main valve oil supply pressure, area ratio, throttle groove width and other parameters on the dynamic response characteristics of the main valve spool displacement, and the influence of pilot flow, control cavity volume, opening and closing frequency and other parameters on the flow stability of the main valve were analyzed. The results show that the response speed of the valve can be improved by increasing the oil supply pressure, opening and closing frequency, reducing the area ratio and throttling groove width；increasing the opening and closing frequency, increasing the volume of the control chamber and reducing the pilot flow can reduce the flow fluctuation of the main valve and improve the stability of the output flow.