The invention discloses a measuring 
system and method for obtaining the inherent frequency of a cycloidal gear of a speed 
reducer under different working conditions. The 
system comprises a fine adjustment displacement mechanism, a magnetic 
torque motor power device, a detection special pin wheel housing, an acceleration sensor, 
strain gauge sensors, a sensor, a 
vibration exciter, a vibration meterand a measurement and 
control system. The magnetic 
torque motor power device and the 
vibration exciter are oppositely arranged on the fine adjustment displacement mechanism; the magnetic torque motorpower device is connected with the to-be-detected cycloidal gear; the acceleration sensor is arranged on the outer surface of the to-be-detected cycloidal gear, the 
strain gauge sensors are respectively arranged at the 
tooth root parts of the to-be-detected cycloidal gear and the detection special pin wheel housing, the output end of the 
vibration exciter abuts against the side end surface of theto-be-detected cycloidal gear, the vibration meter is arranged on one side of the to-be-detected cycloidal gear, and the 
force sensor is arranged at the front end of the vibration 
exciter; and the measurement and 
control system is respectively connected with the acceleration sensor, the 
strain gauge sensors, the vibration 
exciter and the vibration meter. On-line rapid measurement of the vibrationinherent frequency of the 
reducer cycloidal gear under different working conditions is realized, the 
measurement precision is high, and the operation is simple.