The utility model provides an automatic purging device of a circular cooler, which is characterized in that an inner ring purge device and an outer ring purge device are respectively mounted on the outer sides of an inner ring and an outer ring of the circular cooler, and each of the inner ring purge device and the outer ring purge device consists of an upper spray pipe, a lower spray pipe, a compressed air pipe and an opening adjusting switch; the compressed air pipe is laterally connected with an upper spray pipe through an opening degree adjusting switch, the outlet end of the compressed air pipe is connected with a lower spray pipe through the opening degree adjusting switch, the other end of the compressed air pipe is connected to an air compressor pipeline, and the opening degree adjusting switch is connected with a PLC provided with an automatic purging control module. According to the utility model, online automatic purging is realized, the hidden danger of accidental shutdowncan be eliminated, the service life of equipment is prolonged, and the post labor force is saved.