Abstract: Underground storage of liquefied petroleum gas (LPG) is a complicated one of all kinds of underground engineering.Stability of the surrounding rock mass is one of important factors to make sure the success of the engineering.The stability of the surrounding rock mass depends upon its strength and deformation properties as well as the situation of stress convergence in it, and the key is the integrality of the rock mass.In this paper, the quality of the surrounding rock mass is estimated by the method of synthetic classification with multiple parameters.The stress and deformation fields in the section of the underground storage to be open are analyzed with numerical simulating.It is revealed that the strength and the anti deformation capacity of the surrounding rock mass as a whole are suitable to the demand of the project.