In order to solve the problem of speed down-regulation of an aeroengine under the condition of large and slow speed,the speed regulator was taken as the research object,and the model was built on the AMESim platform according to its mechanical mechanism and working principle.The accuracy of the model was verified by simulation using the test results and speed feedback regulation characteristics.After that,the mechanism of the fault was analyzed.Through simulation,it was determined that the main influencing factors were throttle angle,engine inlet temperature,centrifugal fly weight structure parameter change,and spring stiffness coefficient attenuation in the regulator.Combined with the actual working conditions,the above three faults were eliminated.Finally,the optimization schemes such as adding preload compensation to the spring in the regulator and replacing with the new material were given to solve the fault problem.