The production capacity of open-pit coal mines is an important parameter of mine design and development. Production capacity planning is closely related to the economic benefits of mining enterprises. Therefore, it is greatly significant for open-pit coal mines to determine a reasonable production capacity. Determining reasonable production capacity is a complex system engineering problem. Involving the resource conditions of the mining area and various technical and economic factors inside and outside the mining area, it’s of great necessary for open-pit coal mines to combine the shape of the mining boundary to make a reasonable plan for the mining district division and the mining procedure. To rationally plan the production capacity of open-pit coal mines, this study analyzes the relationship among the working face length, the annual advancing speed and the production capacity for the first time, constructs a production capacity function relationship model, and determines the influence of coal seam thickness and working face length on production capacity under the constraints of mining range. The Baorixile open-pit coal mine as an example to illustrate an engineering application in detail. According to the distribution and mining situation of coal seams in the mining area, the remaining unmined parts are divided into four regions. The established function model is used to analyze each region's production capacity, and the four regions' production capacity ranges are determined respectively. On this basis, three mining district division plans for the Baorixile open-pit coal mine are proposed. By analyzing and comparing the stripping ratio, service life of the mining district, fault influence, difficulty of transition connection in the mining districts, the convenience of transportation system layout and other indexes and influencing factors of each plan. Plan 3 is determined to be the technically and economically feasible optimal plan for the mining district division and the mining procedure. According to the capacity relationship of each region, the production capacity planning results of each mining district in Plan 3 is determined as follows: the production capacity of the 3rd mining district is determined to be 30 ~ 35 million t/a, the production capacity of the 4th mining district in Region 1 is 20 ~ 31 million t/a, and the production capacity in Region 2 is 24 ~ 33 million t/a, the production capacity of the 5th mining district is 20 ~ 27 million t/a. The practical performance of the relationship model of production capacity in open-pit coal mines is proved.