In order to solve the problems such as weak linkage between construction schedule and cost, lack of effective monitoring on schedule and cost during construction, difficult to find the deviation and adjust construction plans in time, this paper introduced a method which applies BIM technology and improved earned value method to construction schedule-cost joint control of RCC dams. By establishing a 3D model of the dam, using Primavera 6. 0 software to prepare a construction schedule and calculate the construction costs, and importing construction schedule and cost information into Navisworks software, the relevance matching of the 3D model and the schedule-cost information was realized. Also a 5D construction schedule-cost information visualization model and a dynamic joint management platform based on BIM during construction period was established. Secondary development plug-ins based on C#. NET and API interface can realize analogue simulation of the schedule-cost and visual information query at any time such as construction appearance and schedule, cost, resourceallocation, pouring strength of the placing unit. Monitoring the dynamic changes of improved earned value indicators, early warning during construction and adjusting construction plans can realize schedule-cost joint control during the construction. The engineering application verifies the practicability and superiority of the technology, which possesses the value of popularization.