The accurate shape and position of cavities in an underground mine are important factors that could affect the reliability of numerical modeling analysis used to assess the stability of such structures. The traditional numerical stability analysis of underground mine openings either considers the cavity shape as a regular geometric object, which is determined during the design phase, or uses a simple model created for analysis purposes, both of which affect the accuracy of numerical simulation results. In this paper, a cavity monitoring system (CMS) survey is carried out to obtain the actual three-dimensional shape and the true position of mining excavations. The 3D digital terrain model (DTM) of the suite of mining cavities is then created in the mine design software Surpac. A new and integrated approach to determine the stability of the underground cavity based on the DTM and FLAC models is presented. A case study conducted in an underground copper mine confirms the efficiency and reliability of the proposed method.