Abstract: In this paper,an electronic control unit(ECU) used in vehicle-used natural gas engine is developed independently.A series of starting tests and idle speed tests are done with refitted JL465Q5 engine.AVR single chip is adopted as the core controller.Multiple tablets type is adopted by the ECU.Air bypass valve opening degree is controlled by step motor in order to adjust air inlet quantity when starting and idling.Natural gas allowance is controlled by an electronic injector.Experimental monitoring system is developed as an interface connecting staff and single chip.Speed acquisition system is developed to record starting process accurately in real time.The tests indicate that,more concentrated mixture and higher cooling water temperature are beneficial to cold start for natural gas engine.Incremental PID control algorithm applied to idle speed with closed-loop control for natural gas engine is efficient and effective,and the control effect is better.The experiment results show that the ECU of autonomous development and the speed acquisition system are practical and feasible.