A testing system of exercise machine includes a control signal source and an exercise machine. The control signal source includes a remote control device saved with a plurality of testing commands. The exercise machine includes a control unit and a plurality of driving units. The control unit includes a first controller received in a control panel of the exercise machine, and the first controller generates an error code corresponding to one of the driving unit when the exercise machine malfunctions. The testing commands respectively correspond to different error codes. The remote control device sends an acquiring command to the first controller to obtain the generated error code, and sends the testing command which corresponds to the error code to the first controller to test the corresponding driving unit, and a testing result is sent back to the control signal source. Whereby, the efficiency of testing could be improved.