In addition to adapt deposit geological conditions and ensure production safety, the selection of mining method should as far as possible to improve the economic benefit and social benefit. Therefore the selection of mining method must consider many indexes and factors. According to the actual situation of the project of phosphorus mine field, a total of 14 factors, such as mining capacity, mining efficiency, mining cut ratio, attached ore ratio, unit explosive consumption, caving ore amount, loss rate, dilution rate, cost of extraction, cemented filling percentage, the degree of management difficulty, mining preparation time, degree of adaptation, and safety level, are used as measuring indexes, and the unascertained mathematics theory is used to optimize the selection of five mining methods in Kaiyang phosphorus mine. These methods are in-pulse mining non-pillar contact sectional filling mining method, integrated method of room and pillar type joint out mine-medium-length hole cross cut and afterwards filling mining, integrated method of medium-length hole cross cut and afterwards filling mining, integrated method of medium-length hole cross cut and afterwards filling mining in intra-pulse roadway, integrated method of medium-length hole cross cut with piecewise continuous mining and afterwards filling mining. The results show that the in-pulse mining non-pillar contact sectional filling mining method is the best among them, and the rest of methods take a second place. The optimal results provide a strong theoretical support for safety and effective mining of Kaiyang phosphorus mine.