Abstract: According to the electrical load characteristics in the coal mine,a sequence of the hybrid DC power system voltage is proposed,and the analysis indicates its rationality from the power supply capacity and power supply distance.A coal mine Hybrid DC power supply network topology is put forward to enhance the reliability of distribution network in coal mine power system.In addition,the key technologies for building hybrid DC power supply system in coal mine are summarized and analyzed,such as distribution modes,connection modes,grounding modes,key equipment,operation control strategies and relay protection technologies.Finally,the feasibility of implementing a hybrid DC power supply system in coal mine is briefly analyzed.