Liquefied natural gas (LNG) storage tanks are critical facilities for storing liquefied natural gas, making the monitoring of their outer walls essential for ensuring safety and structural integrity. Currently, deformation monitoring of LNG storage tanks primarily relies on total station measurements or terrestrial laser scanning, which suffer from low measurement efficiency and limited tank coverage. An analysis method was developed for LNG storage tank outer walls based on multi-source point cloud data fusion. By employing four data acquisition techniques—total station, terrestrial laser radar, airborne laser radar, and UAV oblique photogrammetry—and utilizing feature-based random sample consensus (RANSAC) and iterative closest point (ICP) algorithms, multi-source point clouds were accurately registered into a unified coordinate system to construct a 3D model of the tank outer wall. Quantitative analysis of tank inclination and deformation was conducted through segmented fitting and ovality calculations. Results indicate that the LNG storage tank exhibits a tilt variation of 2.58° and a deviation of 27 mm in the azimuth direction of 321.980°. The tank shows a slight tendency to tilt from the northwest. The average ovality of the LNG storage tank is 0.053%, and the average inclination and deviation of 27 mm both meet standard requirements. The recommended action is to conduct regular monitoring of the LNG storage tank. If measured values exceed standard limits, measures such as grouting reinforcement, additional support, hydraulic jacking, or gravity balancing can be implemented.