The present invention provides a method of hot switching data transfer rate on the bus to hot switch the data transfer rate of the bus between the control chips without the process of RESET. When the bus between the control chips demands a large amount of data transfer, the bus is hot switched to a higher data transfer rate to fulfill the data transfer requirement. Contrarily, when the bus between the control chips demands less amount of data transfer, the bus is hot switched to a lower data transfer rate to save power consumption.