A reasonable boundary of open-pit mining is directly related to mine economic benefit,and the delineation of the boundary is a complex job.Based on the geological data of a gold mine,a three-dimensional solid model of the surface and ore body was built using 3DMine software.Based on the geological data and the solid model,the model was evaluated using the distance power inverse correlation method for grade storage calculation,and the open-pit mining boundary was defined by the actual occurrence conditions of the deposits,technical conditions for development,costs and market economic characteristics,through continuous optimization,to derive the optimal open-pit mining boundary of the mine.The application of the software,which not only alleviates the workload of the designer,but also avoids the error caused by the difference in the designer’s level,will have a realistic guidance on mine design and actual production.