A serial communication method is applied in a computing device to communicate serially with any external serial device. The computing device includes a baseboard management controller (BMC) and an operating system (OS). The BMC includes at least one physical serial port. The method generates a virtual serial port for the OS by emulating serial port functionality of the physical serial port. When the BMC is initializing the physical serial port and a serial device is connected to the physical serial port, an interrupt handler is activated to handle an interrupt triggered to the BMC by the serial device. The interrupt handler is deactivated when the physical serial port has been initialized by the BMC.