The invention discloses an outdoor underground three-period mining method of an inclined, thick and large
mineral deposit. The outdoor underground three-period mining method comprises the steps of dividing a life cycle of the mining the
mineral deposit into an outdoor mining period, an mining transition period shifting from outdoor mining to underground and an underground mining period by the following two steps: creating an outdoor underground mining boundary division formula, according to a relationship between a limit
stripping ratio function and an economic
stripping ratio function, determining an outdoor underground mining boundary, and distinguishing the dividing of the life cycle of the mine; and on the basis of outdoor underground mining boundary division, determining a mining opportunity in each of three mining periods. According to the outdoor underground three-period mining method, three mining periods are subjected to unified
comprehensive planning and designing, so that when the outdoor mining period is designed, a development
system is considered to be utilized in the subsequent underground mining period, and when the mining operation transitions from outdoor mining period to the underground mining period, favorable factors such as related
engineering and facilities and the like in the outdoor mining period are utilized as far as possible in the underground mining period at the same time. Therefore, repeated investment of the mine development
system in construction can be effectively reduced. The outdoor underground three-period mining method can be widely applied to the mining of medium and thick or thick and large inclined or steep mineral deposits in the industries of black
metal,
nonferrous metal,
coal, chemical and the like.