Aiming at the safety of construction and operation of underground engineering, taking the complex cavern group of a “818 project” as the research background, the first-level evaluation index system of “man-materials-management-environment”, and the second level evaluation index system of 15 aspects such as technical quality of inspectors Technical support , personnel quality , seepage and leakage of cavern group, disease remediation effect, safety inspection , rainfall, etc. were constructed. Four risk levels such as Ⅰ (inadmissible), Ⅱ (undesirable), Ⅲ (allowable), Ⅳ (negligible) for construction and operation of cavern group were put forward, and a two-level fuzzy comprehensive evaluation model for the operation safety of the “818 project” cavern group was established. According to the fuzzy evaluation matrix of four indicators of man, materials, management and environment, combined with the construction and production data, the single-factor fuzzy evaluation matrix and indicator weights of the first and second levels were obtained by AHP method. and the construction and operation safety of “Project 818” cavern group were predicted. The grade evaluation value δ= 2.3445, the risk level is grade IV, that is, the risk is less likely to occur. The research conclusions provide a scientific basis for the construction and operation safety of the cavern group.