Abstract: In view of problems of low measuring precision and no way to upload measuring result existed in troditional detection methods of roof separation, a detecting sensor of roof separation based on industrial Ethernet was designed. The sensor uses two draw-wire displacement sensors to detect deep displacement and shallow displacement of roof separation and uses displacement detection circuit to transform current signal output by the draw-wire displacement sensors to voltage signal for sampling by single-chip microcomputer. The single-chip microcomputer analyzes displacements of deep part and shallow part according to sampled voltage value to get roof separation value which is uploaded automatically through industrial Ethernet to surface monitoring computer. The test result shows that the sensor can realize accurate measurement of displacement of roof separation with ±2.5% measuring error and can upload measuring result easily.