Abstract: The automatic testing method for several parameters of ignition magneto in operation speeds was introduced. The hardware was based on single chip microcomputer. The ignition magneto was drived by AC frequency converter, and the photoelectric encoder was used for rotational speed testing and rotational angle testing, so that acquisited ignition pulse signals can be handled. The testing algorithm was given, and the anti interference algorithm for the ignition signal testing and the method to control rotational speed and testing sequence were mainly elaborated. By using this method, the time for a complete testing was about 127 seconds, the testing error for number of ignition times was totally eliminated, and the error for ignition angle was less than ±1° when the resolution of photoelcetric encoder is 360 ppr. If encoder of higher resolution is used, less error in ignition angle testing will be obtained.