The invention belongs to the technical field of cost management and specifically discloses a cost management system of a BIM project. The system comprises a data acquisition module, wherein an outputend of the data acquisition module is electrically connected with an input end of a data conversion module and an input end of a central processing unit; the central processing unit is bi-directionally and electrically connected with a processing center; the processing center is bi-directionally and electrically connected with a storage module; an output end of the central processing unit is electrically connected with an input end of a data distribution module and an input end of a model building module respectively; an output end of the data distribution module is electrically connected withan input end of a remote terminal. In the system, by adopting a BIM technology, data building, contract data and data alteration in a construction process are integrated, cost estimation, target costcalculation and cost risk management are achieved, and effective cost control is achieved, so that the working efficiency is improved, and the accuracy of cost data is improved.