Abstract: Accurately constructing the three-dimensional terrain of the open-pit mine and objectively reflecting the dynamic characteristics of the open-pit mine during the mining process are great significance for improving the efficiency and information level of the open-pit mine production management.According to the characteristics of the open-pit mine terrain，an improved modeling method was proposed based on the convex hell algorithm.In this method，the three-dimensional terrain fine model was optimized by using spatial features as constraints.Based on the three-dimensional terrain fine model，this article further proposed an improved algorithm for earthwork calculation against the limitation of three-dimensional volume calculation in geographic information software ArcGIS.Taking Baojixier open-pit mine as the experimental area，according to the the survey data of the topographical parts，the 3D terrain fine model construction verification experiment was carried out.The experimental results show that the modeling method can improve the construction efficiency of the 3D terrain model， and optimize the 3D terrain model with the edge as the focus which improves the geometric accuracy of the model.By comparing and analyzing the volume change and shape change of the three-dimensional terrain model of open-pit mine in different periods，it provides a basis for quantitative evaluation of open-pit mine mining situation.

Key words: Open-pit mine, Terrain modeling, Convex hull algorithm, TIN, Model volume