Aiming at the problem of constraints between reconstruction range and splicing accuracy when 3D reconstruction is carried out on large-scale equipment in aerospace and other fields, we investigate the combined 3D scanning measurement method based on the guidance of the all-space laser positioning system (ALPS) on the basis of analyzing the fusion of the ALPS and scanning target. The method establishes a global 3D scanning measurement model based on multiple measurement points by Creo and simulates and analyzes the data with MATLAB, then designs the structure of the circumferential combined photoelectric receiver by combining with the receiving characteristics of photodetectors for laser signals in the full-space field, and then completes the optimal layout design of the receiver based on the accessibility. Finally, a 30 m×30 m experimental platform for the fusion of ALPS and scanning target is constructed, and the measured standard bat and Zeiss standard ball are used as the measured objects to verify the feasibility of the research method. The simulation and experimental results show that the optimal number of receivers needed for the global measurement system is N=6, the measurement accuracy is better than 0.5 mm, and the repeatability measurement accuracy is up to 0.02 mm, which provides a basis for the 3D scanning of large-scale equipment.