Abstract: To accurately detect fault by in-seam seismic survey, 10 typical observation system models, belonged to 3 categories of working face interior detection, exterior detection and others, have been built generally according to location, fault strike and detection objective. Moreover, working face interior detection is divided into 7 types according to fault location, fault throw, angle between fault strike and survey line. Afterwards exploration methods, layout of shot and geophones and data interpretation methods have been described. Furthermore, taking two typical fault detection projects as examples, the survey area conditions of working face roadway layout, coal thickness, coal seam occurrence and structural development are analyzed. According to the location and occurrence of faults to be detected, the observation system design was carried out in comparison with the observation system model. The reflection method exploration was carried out in the 11160 working face of Yunding Coal Mine, and the combined penetration and reflection method exploration was carried out in the 25050 working face of Guanyintang Coal Mine. The results of data interpretation and verification show that the results are consistent with those of exploration prediction.