Abstract: Currently, the major landslide monitoring method is single-point monitoring, which can obtain highly accurate monitoring value, however it can only acquire the deformation value of a point other than a region. Therefore, it is suggested that terrestrial laser scanning be used to monitor landslide. To improve the accuracy and reliability of landslide deformation monitoring, the nearest neighboring point search algorithm is proposed to determine the extraction threshold of landslide deformation. After the point error effect is removed, the landslide area is extracted and its size and direction is determined.  A series of numerical simulation and practical scanning have verified the effectiveness of the method.