Abstract: It is critical to make clear fault occurrence for safe production in coal mines. Through drilling underground boreholes to detect a fault in Cuizhuang mine, the relationship of geologic horizon of Tiangang fault was identified. By using the geometric data and planar projection of the seam, the occurrence elements of Tiangang fault including dip, throw and strike were relatively accurately determined, replacing the ordinary vague extent representation of fault occurrence. The method used in the paper is simple in the principle, easy to master. Its calculation results are more accurate and more reliable than the existing geologic data. It provides technical support for realization of refined mining in coal mines and has reference value for mining areas with similar geologic and mining conditions.