Abstract: A digital electronic control system RST-6 for WZ6G engine, in which a CMC-80 microcomputer and a step-motor driven by a needle metering valve are used. In order to enhance the accuracy of control and the speed of system response, variable coefficient dual-speed control with PID feedback is adopted. A large number of integratedelements and anti-interference measures are employed to increase the reliabilityof the system.The present system has run on trial 4200 hours in the Zhongyuan oil field.