In order to improve the effect of engineering surveying and mapping system, this paper improves the three-dimensional point cloud technology. The problem of inaccurate measurement results caused by complex terrain is solved. At the same time, an improved greedy projection triangulation communication reconstruction algorithm is proposed. That is, while homogenizing the point cloud density, the point cloud redundant point removal algorithm is used to remove the overlapping points. The registration algorithm is applied to the engineering system. Combined with the improved algorithm, the system framework of the engineering surveying and mapping system is constructed, and the system algorithm is verified by a simulation example. Finally, combined with the actual situation of engineering communication surveying and mapping, the performance verification of the system is designed and tested, the research results are counted, and the algorithm is evaluated. The system carries out engineering surveying and mapping through three-dimensional point cloud and improves the surveying and mapping accuracy through registration algorithm. The engineering surveying and mapping system based on three-dimensional point cloud and registration algorithm proposed in this paper has high accuracy and can meet the needs of practical engineering. The system solves the problem of inaccurate measurement results caused by complex terrain, complex terrain, and complex terrain.