With the rapid development of China’s electric power industry, the cost management of electric power projects, which is closely related to the power grid transmission and substation projects, has become more and more important. Do a good investment feasibility analysis of power projects. Optimize power engineering design. Reasonable determination of power project cost and effective control of power project cost are the main problems to be solved by the project cost management of power grid transmission and transformation projects. In this paper, DCN-BIM model is established based on DCN algorithm as the theory. A detailed calculation and analysis of the influencing factors and stage share of the cost management of power grid transmission and substation projects is carried out. Through calculation, it can be seen that the share of power products in the project cost is about 15.43% due to their special characteristics. The lowest cost share in the project cost is the project tender. Its share is only 10.03%. The highest cost share is for equipment materials. Its cost share is as high as 51.34%. The design phase accounted for 23% of the cost. The lowest cost share in the bidding phase was only 21%.