Abstract. The construction enterprise is one of the important management ways, and it also is main mean of controlling the project schedule, quality and cost. Although outsourcing can be good for integration of resources to realize the optimization of resources, due to the contracting enterprise and the unbalance of interest conflict between them and other factors, the risk is certain to bring. The correct evaluation to the risk is an important basis for decision-making. This paper is used by using information diffusion method to the construction risk analysis on the exploration, and analyzing the error, to proof that the information diffusion method in building construction risk analysis is of the application of the feasibility, which can make full use of the existing information. By adjusting the domain of discrete points the density of the degree so that the request reaches the required accuracy.