Abstract: In order to evaluate the stability of the construction site above the old goaf scientifically and reasonably， this paper evaluates the construction site stability of Wuyun expressway goaf based on cloud model and fuzzy hierarchy analysis process （FHAP）.First of all，six independent factors that affect the stability of construction site in goaf section of Wuyun expressway are screened，they are ratio of deep and thickness，intensity of strata，structure complexity，hydrological characteristics，stopping mining time and relative position，and the influencing mechanism of each factor on the stability is analyzed，the stability evaluation model suitable for the study area is established.Secondly，cloud model is adopted to determine the membership degree of evaluation indexes，which can effectively avoid the influence of data randomness and uncertainty on comprehensive evaluation.Thirdly，the weights of evaluation indexes are is determined based on fuzzy hierarchy analysis，so as to reduce the influence of subjective factors in data processing and improve the objective credibility of the analysis results.Finally，the stability evaluation model established in this paper was used to evaluate the construction site stability of Wuyun expressway goaf.The study results show that the evaluation results of this evaluation method are consistent with the actual engineering situation，and it provides support for the design，construction and maintenance of the goaf of Wuyun expressway.

Key words: Goaf, Cloud model, Fuzzy hierarchy analysis, Stability evaluation