The hole layout design of medium-length hole blasting in underground mine directly affects the blasting efficiency and production cost.Previous research has proposed the optimization algorithm based on the single source & shortest path which greatly improved the efficiency of hole layout design optimization.However,the proposed methods still cannot fully meet the demands of actual application.In this paper,the correlation between the hole layout and the medium-length-hole blasting parameters was analyzed.The bottom distance between the holes was taken as one of the main control parameters.Based on dynamic programming of the shortest path from multiple sources and Floyd algorithm,an algorithm model for optimal layout design of fan-shaped medium-length hole blasting was established.The proposed model solved the problem of the hole layout optimization of fan-shaped blasting hole design with preset specific hole parameters.On this basis,the optimal design program module of medium-length-hole blasting was re-developed using the AutoCAD platform which was successfully applied to an iron mine.