The invention discloses a detecting platform capable of simulating the vibrating fault of a harmonic reducer. The detecting platform comprises a power transmission device, a harmonic reducer simulator, a power loading device, a damping device, a positioning device and a sensor group. According to the invention, three types of sensors are adopted for collecting signals, and are respectively two electric eddy sensors, four acceleration sensors and a pressure sensor; the two electric eddy sensors are fixed obliquely above two sides of an input shaft of the harmonic reducer simulator by forming an angle of 90 degrees so as to perform detection on the trail of the axis of the input shaft; and the four acceleration sensors are arranged at foot stalls of a testing support seat and reflect the working characteristics of the harmonic reducer by collecting the vibrating acceleration of the foot stalls. The platform realizes simulation on the harmonic reducer in working conditions of different loads and different reduction ratio, can detect the vibrating signal in various different working conditions, and can obtain the overall working performance of the harmonic reducer by carrying out processing and analysis on the signal. The platform is compact in structure, safe and reliable in detection process, and strong in detection result feedback.