Abstract: As an emerging active remote sensing technology, ground-based 3D laser scanner is gradually applied to various fields such as surveying, and it is the main way to obtain ground target data with the advantages of high accuracy and high efficiency, but the coordinate system of LiDAR point cloud data acquired by it exists randomly relative to the internal coordinate system of the instrument system. In order to solve the problem of coordinate system conversion in quantitative analysis of seismic damage information of building LiDAR point cloud data, this paper establishes an origin coordinate system conversion method based on three-dimensional coordinate system conversion matrix for LiDAR point cloud data extracted by filtering, denoising and segmentation of building independent walls. Comparing the conversion results with the results of the instrument supporting software, we verifies that the results of the coordinate system conversion algorithm coincide with the horizontal line in the X-axis direction and are better than the software conversion results. The establishment of the method in this paper reduces the human error factor in the data processing, improves the precision and accuracy of the coordinate system conversion of foundation LiDAR point cloud data, improves the efficiency of post-earthquake LiDAR point cloud data processing and analysis of buildings, and lays the theoretical foundation and technical support for the later quantitative analysis and determination of building damage information.