Abstract: In order to solve the difficult problem of on-site upgrading of sensors in coal mine safety monitoring system, ISP technology and IAP technology are compared and analyzed. It is concluded that IAP technology is more suitable for on-line upgrading of mining sensors. On this basis, a method of sensor online upgrade through the existing transmission network of coal mine safety monitoring system is established. The ground host computer transmits the upgrade program of bin to the monitoring substation for temporary storage through Ethernet, and then the monitoring substation sends it to the mine sensor need to be upgraded through CAN Bus. The sensor MCU flash is reasonably divided into three storage areas, and the Bootloader program of IAP area is used to realize the program jump between APP1 area and APP2 area, so as to achieve the purpose of mine sensor upgrade. At the same time, the transmission fault-tolerant mechanism is designed to ensure the stability of mine sensor online upgrade.