Abstract: The residual deformation of the surface on the goaf will bring risks to the expressway above the construction site and seriously threaten the operation safety of the expressway.It is of great significance to accurately evaluate the stability of the construction site of the goaf for the overhead expressway to avoid risks.First of all,principal component analysis and residual (PCA-RA) are used to carry out dimensionality reduction analysis on the stability evaluation indicators of the construction site on the goaf,and several principal components with the largest contribution rate are extracted,which can eliminate the redundancy among evaluation indicators and reduce the workload of evaluation process.Secondly,the cloud model is used to determine the membership degree of principal components,and the stability level of construction site can be evaluated based on the principal of maximum membership degree.Finally,the fuzzy entropy is introduced to determine the complexity of the evaluation results.The model established in this paper is used for the stability evaluation of the construciton site of Mianluan Expressway.The results show that:① The first four principal components of cumulative contribution rate is 87.278% after dimensionality of the evaluation indicators data by principal component analysis,which can completely represent the information of the original indicators;② The stability state of the construction site on the goaf of Mianluan Expressway is mainly stable and basically stable.The research results can provide a theoretical basis for the later management and monitoring of the construction site and ensure the operation safety of the expressway.