Based on the unascertained measurement theory, a safety evaluation model of the boundary pillar is built. Under the geological conditions and the engineering situation of the mine, which goes from an open -pit to the underground mine. 7 main factors that influence the stability of the boundary pillar are taken into consideration, including the thickness of the boundary pillar, the compressive strength of the ore, the tensile strength of the ore, the open-pit depth, the joint distribution, the mining method of the underground mine and the seeper of the open-pit. The unascertained measurement function is obtained based on the actual situation of the mine; the weights of all indexes are calculated by using the entropy theory, the safety evaluation results of the boundary pillar can be obtained based on the credible degree recognition criteria. Using this model, the safety of the boundary pillars of three typical mines is evaluated. It is indicated that the unascertained measurement assessment results agree well with the actual records, and the scheme of the Xinqiao Mine's boundary pillar is feasible. The results show that this model provides an effective method to evaluate the safety of the boundary pillar. The establishment of the uncertainty safety evaluation model highly depends on the grading standards and there is no uniformly accepted grading standards yet, further studies are needed to solve this problem.