Abstract: The work on principle and constitution of trouble simulate system in computer controlled for electronic controlled engine is introduced in this paper.It expounds the main structure character and design methods of computer control unit,circuits of trouble simulate and showing board about the trouble simulate system in computer controlled.Trouble simulate system of computer controlled for electronic controlled engine is a device on circuits of automobile engine computer system that is changed.It can continuously produce various kinds of simulate trouble of the sensor,actuator,electronic control unit and control circuit.It supply abundant inspect content and convenient inspect port for user.