Abstract: In order to monitor the double chain drive synchronicity of the chain rake picking up mechanism, a double chain drive synchronicity monitoring system based on eddy current sensor was designed. The monitoring system takes STC89 C52 MCU hardware system as the lower machine and obtains the speed information of the chain raking mechanism and the power shaft through the eddy current sensor and Hall sensor, respectively. The system determines the running state of the chain raking mechanism of the film receiving machine. It transmits the state information to the human-machine interface of SG121-BGCM industrial computer for real-time display through the HC-12 wireless module.The laboratory test shows that when the speed of the film collecting chain harrow is 168 r/min, the accuracy rate of the jumping gear monitoring of the chain picking mechanism is more than 96%.The field experiment shows that the accuracy rate of the jump gear monitoring is more than 95% when the forward speed of the film collector is 8 km/h, and the speed of the chain harrow picking mechanism is 168 r/min. The monitoring system realizes the real-time and high precision monitoring of the running state of the chain-rake type residual film recovery machine, which is helpful to improve the operation reliability of the residual film recovery machine.