Abstract: In order to solve the problems of high cost and untimely manual cleaning of nightsoil caused by large amount of defecation in large-scale pig farms, the author designed an automatic piggery manure cleaning device. The device included a cleaning machine, a traction mechanism and a control system; STC89 C52 microcontroller was used as the control unit; sensing technology was used to detect the liquid level in the fecal canal; Lora communication technology was used to make the control unit communicate with the liquid level sensor to trigger the motor to start, and realize automatic piggery manure cleaning. The influence of different materials and thickness on the flatness variable of the manure scraper was analyzed by ANSYS 2021 R1 software. The results showed that the shape variable was the smallest when the overall thickness of the manure scraper was 7 mm, which was 0.303 21 mm. The material of the manure scraper should be high quality carbon structural steel（grade: 08 F）. The control unit can realize automatic piggery cleaning. The device had a good effect on cleaning piggery manure, and the overall system runs stably. The results indicated that the automatic manure cleaning device can meet the requirements of pig farms.