Abstract: In this paper, an adaptive spark timing control system for gasoline engine controlled by micro computer is introduced. It can be used for getting the best igniting time of the gasoline miniengine.The hardwares of the system consist of magneto sensor,intel8098,2864 E^２PROM and capacitor igniting system.The results from steady state engine bench test show that using the adaptive spark timing control system , the fuel consumption decreases by 2%～7%,the largest power increases by 6 % and the biggest to rsion increases by 2%。