Abstract: Traditional open-pit mining boundary features fixed slope with benches and planar bottom. Taking for example the open-pit mining slope of Chahe Tin Mine located in Huili County, Liangshan Prefecture,Sichuan Province, this paper presents the process and methods of research and design for open-pit mining boundary with fixed slope, no benches and non-planar bottom, and proves its applicable conditions and measures to be taken for safety purpose in production. It also gives an exposition of its technological and economical effectiveness.