Abstract: A large underground cavern group as historical relics generally lasts for hundreds of years or even thousands of years，which level of security is different from general rock mass engineering，under the influence of various factors，large cavern group of rock mass structural stability and strength are reduced，eventually lead to the instability of rock mass， damage，therefore，it is necessary to conduct stability analysis of rock mass and reinforce technique study of the large underground chamber group.The large underground chamber group construction project belongs to the large underground rock mass excavation project.Before the excavation of the rock mass project，the engineering geological survey results show that the overall stability of the rock mass of the chamber group is good，and the stability analysis is carried out by the stability empirical evaluation method，it is found that the overall stability of the chamber group is good.Based on the above discussion results，the three-dimensional numerical simulation method is used to evaluate the overall stability of the chamber group.The calculation results are basically consistent with those of the engineering geological survey and the stability empirical evaluation method.The surrounding rock of the large chamber group after excavation is generally in a stable state.In view of the local fault fracture zone and the instability hidden danger of the local block in the adit，the reinforcement scheme of anchor net spraying，which is based on the combination of anchor bolt， grouting and pouring concrete is proposed，it is help for effectively ensuring its safety and stability.

Key words: underground chamber group, joint fissure, stability analysis of rock mass, numerical simulation, grouting reinforcement