Abstract: In consideration of a lack of protection device for scraper conveyor in Tunlan coal preparation plant,based on analysis of chain breakage,a chain protection device for scraper conveyor is designed,which can detect the faults in advance to avoid chain breakage on either side of scraper conveyor and protect the chain on the head of the equipment rolling up. The application shows that this device discovers early faults in time,and tackles them completely,which insures normal production of the plant,and brings remarkable economic benefits.