Based on the reconstruction project of submerged section of S508 Provincial Highway in Xizang, this paper builds a high-precision 3D geological model on the basis of 3D GIS terrain. Based on a three-dimensional geological model, the independently developed Revit platform geotechnical auxiliary design tool and 3DE platform were used to develop a digital design system for transportation engineering. Slope support design and bridge tunnel design were carried out separately, and the models were managed and integrated in the "Survey and Design Management System" and "Guikan Digital BIM Comprehensive Consultation System". The deep integration and application of transportation engineering BIM models and GIS+GIM models were achieved, exploring a collaborative design application route of multi professional digital technology, saving time and cost of coordination and communication in various professional design processes, and improving design efficiency and quality.