In view of poor visualization ability and computability of the traditional mine 2D design, a stope 3D visual design which combines the 3D mining software and the Cavity Monitoring System (CMS) is proposed. First, the shape of the cavity is obtained by CMS, to build a local geological model of the stope. Then, a 3D model of the pillar is built by Boolean operations of solid models and the local geological model. Based on this, a preparatory arrangement is obtained. Finally, a full 3D visual design of the stope is achieved. A medium-to-long hole blasting design is carried out by CMS and Surpac software in the E2-3 stope of some metal. First, pillar sections of the stope are acquired quickly in Surpac. Then, a blasting design database is constructed, and a medium-to-long hole blasting design of each section is made. Finally, a blasting report is generated. According to statistics, the volume of stope and the amount of explosives are obtained, with explosives consumption being calculated as about 0.892kg/m3, which agrees well with the empirical value. The practice shows that this method can well determine the pillar boundary in the pillar extraction with visualization, which the traditional design is dificult to achieve, and it is also convenient.