Abstract:This paper combined the method of probability,mathematical statistics,and technology of computer with theory of Project cost risk management,based on the theory of initiative control and took the Crystal Ball as an assistant tool to analyze the risk of cost management in a certain project,verify the actual effect of the model when it is used to the practice,give some suggestions to evade risk in a certain degree and mend the existent decision model to improve the efficiency and precision of analysis of cost management risk.