Abstract: In view of defect that location way of sampling head of traditional bridge-type train coal sampler is inaccuracy, an automatic location system of sampling head of bridge-type train coal sampler was designed based on PLC and shaft encoder according to detection principle of encoder for location and speed of equipment. The hardware configuration and software diagram of the system were given. The system can accurately calculate position and speed of the sampling head by detecting pulse signal of the shaft encoder, and can real-time display numerical value on HMI through touch panel and embedded configuration software.