Cjqmxc-f high voltage common box type bus duct system is suitable for power supply system with AC 50-60Hz, voltage 3.6-35kv and rated current 400-6300a. It has excellent short-circuit resistance. Due to the protection of aluminum (or weak magnetic steel plate) shell, it can effectively reduce the structure heating caused by eddy current or circulation, reduce the temperature of enclosed bus shell, reduce the power loss, improve the current carrying capacity and reduce the electric power. The structure of the bus duct is advanced, and the installation and maintenance hole can be arbitrarily set at the upper or lower part of the enclosed bus. For the large current indoor enclosed bus, ventilation louvers are set at both sides and the lower part of the shell to enhance heat dissipation and reduce temperature rise. By using double insulation and multi-point connection of the shell, the maintenance workload is obviously reduced and the safety performance is significantly improved.