With the development of computer technology and the rising of the industry control level, the bus application field is more and more extensively. In potroom, the control system layout for aluminium electrolysis pot is like that, pot controller is installed in potroom but the supervision unit is installed in main controller room which with the distance of 1 kilometer from the potroom. The CAN bus is used for communication between the supervision unit and pot controller. Due to the badly site environment, especially the strong magnetic field and high dust is exist, high speed rate signal will reduced seriously and gets strong influence during the period of long distance transmission. With the purpose of reducing the error in the control system and increase the reliability and the security of the signal, it has to overcome above mentioned bad affect as follows: correspondent equipment should be add erect in the transmission line to get the function of isolate and drive. The article gives expatiate on the adding equipment that installed between the production site and main controller room in aluminium electrolysis control system, which is bus repeater.