Geotechnical investigation is the key module of infrastructure construction, which determines the safety and quality of engineering construction to a large extent. BIM technology combined with 3D geological modeling is a new idea and direction in geotechnical investigation. In view of the problems existing in the traditional two-dimensional display mode, this paper studies the following contents: First, research BIM technology, including the main applications and core advantages of BIM technology. Then, two core techniques of 3D geological modeling are studied. The discrete smooth interpolation algorithm and Kriging interpolation algorithm are studied and compared. The mathematical models of semi-variation function and experimental semi-variation function are constructed, and the theoretical models are fitted to the values of experimental semi-variation function. Finally, based on BIM technology and 3D geological modeling, this paper studies the application of the combination of BIM technology and 3D geological modeling in geotechnical investigation and visualization, including visualization technology flow, 3D visualization method, creation of 3D structure, establishment of visual model and engineering geological analysis. Research has found that integrating BIM technology with 3D geological modeling can achieve information-based management of geotechnical engineering survey projects, improve the risk warning ability of geotechnical engineering survey projects, and reduce errors and economic losses during the construction process.