This paper takes the infrastructure projects in the electric power industry as the research object, and explores the full-process cost dynamic management system of engineering projects under the BIM 5D technology. Applying the BIM model as the carrier of cost information, and integrating the cost information of different stages based on the theory of bill of quantities, thereby the paper establishes a dynamic cost data template and a cost control system for the entire life cycle of the project. The new full-process cost dynamic management system under the BIM 5D technology can achieve virtual-real linkage and collaborative analysis of multi-source heterogeneous information.