The utility model discloses a colliery belt conveyor of off tracking state can monitor is to the problem that colliery belt conveyor fault monitoring product operational capability is not enough. Theutility model discloses a contain the response of belt conveyor, off tracking and judge device, signal transmission module and alarm device, wherein the off tracking response judge the device and fixin belt conveyor's frame that device passing signal line establish ties in proper order signal transmission module and alarm device are judged in the off tracking response, the off tracking response judges that the device contains centring idler, travel switch and delay timer, and wherein centring idler one side is punished near the conveyer belt central line and do not is equipped with two sets of travel switch, and it distributes about the center line symmetry of conveyer belt respectively, and travel switch's signal output part passes through the wire with the signal input part of delay timer and links to each other, and the signal output part of delay timer links to each other with signal transmission module, travel switch 0 in proper order. The utility model discloses continuously rectify a period and then send out the police dispatch newspaper when failing to correct the home position with the sticky tape, remind artifical the correction.