Due to the large number of participants in PPP projects, long operation period, large investment and other factors, the project risk factors have a high degree of ambiguity and randomness. In order to accurately carry out the risk evaluation of PPP projects, this paper proposes a risk evaluation method based on cloud model. Firstly, select the main risk factors and establish a risk factor identification system. At the same time, according to the expert evaluation method and principles of comment index, establish the main risk evaluation index system, and then use improved fuzzy analytic hierarchy process method and entropy weight method to obtain the weight of the risk from the subjective and objective perspectives. According to the reverse cloud model algorithm to obtain the digital characteristics of the secondary risk. The digital characteristics of the secondary risk and the weight are combined to finally obtain the digital characteristics of the total risk of the PPP project, and the forward cloud model generator is used to obtain the cloud model of the total risk. Then according to the cloud model, the risk level standard cloud is given, and the risk level is determined by comparing the similarity of the two cloud images. This paper takes the PPP waste incineration power generation project as an example to verify the proposed method. The results show that the method is effective and scientific, which can provide a reference for future risk assessment of PPP projects.