According to the structural features and working modes of the existing seal machine, a new automatic seal machine suitable for schools, government departments and other departments was designed and implemented. The structure design of the seal machine was completed and the working process was given from the following four aspects, namely, successive automatic paper feeding, the integration of sealing and dipping inkpad, the selfadaptive adjustment of sealed pressure and the adjustment of sealing position, and the automatic control scheme based on PLC was put forward. The developed automatic seal machine has been tested and verified. The results show that the whole operation process is stable and reliable, and meets the technical requirements of convenient seal switching, high efficiency of sealing and dipping inkpad, rapid automatic paper conveying and strong adjustment on seal position