In the mining process of underground mines，the work of engineering geological investigation of the roadway is the necessarily for the rock mass stability evaluation. Through the mapped geometric parameters of the structural plane，a computer program was used to establish a three-dimensional model of the structural plane and the underground roadway to analyze the structural characteristics of rock mass. However，due to the complex rock mass conditions of the underground roadway，the limited exposure and variability of rock face orientation in roadways must be taken into account. Traditional methods for the mapping of structural planes such as scan-line mapping and window mapping are restricted by the complex environment of underground engineering that cannot be obtained accurate data. This would result in insufficient quantity and poor quality of the obtained structural plane data，which makes it impossible to accurately analyze the structural characteristics of rock mass in underground roadway. In order to accurately obtain the structural plane information of the underground roadway，3D laser scanning technology was used to research on the detection and identification of rock mass structural planes in underground mine. The work flow of the 3D laser scanning system and its principle，point cloud data processing，and structure plane information extraction was explained. Then，the 3D laser scanning and structural plane information extraction were carried out at the roadways of 1 430 m level，1 440 m level and 1 450 m level of the Dabaiyan area Ⅰ-51# ore cluster of Kafang Branch of Yunnan Tin Co.，Ltd. Finally，the structural plane data obtained by the traditional measurement methods and the 3D laser scanning measurement were compared and analyzed. The results show that the structural plane data obtained by the 3D laser scanning measurement method in underground mine is more abundant，comprehensive and accurate than traditional measurement methods. Using the characteristics of fast 3D laser scanning operation speed and wide scanning range can greatly reduce the working time of surveying personnel in the harsh environment of underground roadway，thereby improving the work efficiency of surveying personnel and ensuring work safety. In addition，the virtual point cloud data of the structural plane obtained by the 3D laser scanning can be directly generated by the post-processing software to directly generate the 3D model of the structural plane，thereby quickly interacting with other rock mass structure analysis software，reducing repeated modeling steps.3D laser scanning technology can provide an efficient method for the engineering geological investigation of rock mass structural plane in underground mine.