The selection of open-pit stope slope angle is the priority prerequisite to determine open-it mining boundary.In light of small slope angles and much resource occupied by open-it slope which is commonly incurred in open-pit stopes,the existing slope angle is optimized to determine optimal slope angle based on rock mechanics and ore body occurrence state in mines.CAD and finite element software are coupled to create the model,and Mohr-Coulomb constitutive relation is used to select several representative sections and analyze the stability based on the displacement variation of different steps during the excavation,and the final slope angle is determined to be 38°-42°.The study provides basis for mining plan optimization.