Abstract: To use digital mineral deposit models as a means to perform a 3D positioning and quantitative study of mineral resources is a new idea and way for looking for buried orebodies in crisis mines. Based on studying and summing up the geological model and metallogenic characteristics of the Koktokay No 3 pegmatite dike, a 3D model of 9 mineralogical-structural zones was constructed for the pegmatite dike with the Mincromine software as the platform, and then a positioning and quantitative study of buried orebodies was conducted by using drilling data. The results show that the Koktokay No 3 pegmatite dike has still potential of exploitation and that there are 60 t of remaining BeO resources with a BeO grade>commercial grade and 63 t of predicted BeO resources, which can provide a resource guaranty of 4-5 years for re-mining of the mine. In the surrounding areas of the ore vein and at depths, the perspective BeO resources are 1118 t with a grade>cutoff grade and the Li2O resources are 241 t with a grade>cutoff grade. These data indicate that the No 3 rare metal pegmatite dike still has great potential for exploration and exploitation. This study also demonstrates the unique advantage of the study based on the digital mineral deposit model in mineral exploration of crisis mines.