In response to the difficulties of processing laser point cloud off-site real-time scanning and on-site absolute coordinate system alignment， a low-cost ground-based LiDAR measurement system is developed by combining the BeiDou/GNSS positioning system and 5G communication technology. The developed measurement system is integrated by LiDAR， a high-precision motor， BeiDou/GNSS receiver module， and a 5G module. LiDAR collects point cloud information， the high-precision motor acquires angle information， BeiDou/GNSS receiver module receives the time， the high-precision motor acquires time stamps using a self-developed time synchronization module， and LiDAR obtains the point cloud and angle file with time tag before transmitting in real-time via 5G communication technology. The terminal performs spatial and temporal alignment of multi-frame point clouds by linear interpolation algorithm through self-developed data pre-processing software， coarse alignment of the multi-station laser point clouds based on BeiDou/GNSS coordinates outdoors， coarse alignment of the multi-station point clouds by single-station feature points in an indoor environment without BeiDou/GNSS， fine alignment using the proximity iteration algorithm to complete overall alignment， and visualization on the self-developed real-time point cloud management and visualization system. The experimental results show that the measurement system achieves real-time off-site scanning and transmission at a transmission rate of 50 Mbit/s by using 5G communication technology. The error of the aligned point cloud is less than 3 mm， which can provide digital infrastructure for real-time applications such as digital twin， monitoring of material and cultural heritage， analysis of construction and operation， and maintenance of large buildings.