Abstract: There are four kinds of fault of scraper conveyor’s chain, which are chain broken, scraper broken, loocked-rotor and chain jumping. In order to detect the fault timely and to ensure stable and reliable operation of scraper conveyor and the safety production in coal mine face, an on-line device, by which the four chain fault can be detected, is designed for chain fault monitoring of double side chain scraper conveyor.The sensor for scraper conveyor's chain fault is designed. The overall architecture of the flameproof?and?intrinsically?safe monitoring device is proposed, which have double MCU, human-machine?interface and Ethernet?interface. Reasonable selection of core components of the device is presented. Core circuit of the device composed of photoelectric isolation circuit, mininum system, pulse signal measuring circuit, etc. is designed. Pulse signal analysis logic is introduced to recognize the faults. Development of the on-line monitoring device can detect the fault of scraper conveyor’s chain timely and provide guarantee for both the life of workers along the convey and the safety production of coal mine.