调速阀一般由定差减压阀和节流阀串联组成。当其工作在大压差、大流量场合下，布置在主回路上的减压阀压力损失大，会带来油液温升等问题。提出一种先导数字调速阀，主阀为流量放大原理插装阀，先导阀为由高速开关阀与定差减压阀串联组成的数字调速阀。高速开关阀为PWM控制数字阀，节流损失小、重复性好、抗干扰能力强。将定差减压阀应用在先导回路，由于控制流量小，可有效解决压力损失大、发热大问题。通过理论推导和仿真研究，验证了该阀可行性，并得出该阀性能与结构参数之间的关系，为其设计提供了理论基础。“,”Flow control valve generally consists of constant pressure difference reducing valve and throttle valve. When it works under the condition of high differential pressure and flow,the pressure loss of reducing valve in-stalled in main loop will get increased and the hydraulic oil temperature will be increased as well. A digital pilot flow control valve is studied in this paper. The main stage is a cartridge valve based on the flow amplifying princi-ple . The pilot stage is digital flow control valve which consists of digital valve and constant pressure difference re-ducing valve. The digital valve controlled by PWM signal has some characteristics such as less throttling loss and good repeatability. The high pressure loss and hydraulic oil temperature will be effectively reduced by using con-stant pressure difference reducing valve in the small flow pilot circuit. Through theoretical derivation and simula-tion research,the feasibility of this valve is verified,and some conclusions are drawn for the relationships between the performance and structure parameters,which provides theoretical basis for their design.