In order to solve the problem of technical precision in landscape planning of complex landscape garden topography, the authors propose a research using 3D virtual scanning technology. The main content of this research is based on the overall architecture of the 3D virtual landscape planning system, the construction of the system architecture, and the optimization of VR design scenarios; finally, through experiments, the feasibility of 3D virtual scanning technology is obtained. Experimental results show that the number of landscape connection points measured by the author is more than 1500, and the accuracy is between 0.2 and 0.6 pixels, indicating that for the mutual connection and orientation between models, the system has a good application prospect in the landscape planning of complex landscape garden topography. The research on 3D virtual scanning technology is proven, and it can meet the application in the landscape planning of complex landscape garden topography.