A method and an apparatus for using a serial port device in a time division multiplexing manner are provided. The apparatus includes a first serial port, a second serial port, a switching circuit, and a signal interface, where the switching circuit selects to receive data sent; the first serial port sends first data to a first serial port device; the second serial port receives second data sent by a second serial port device, and when it is determined that the second data indicates that the second serial port device needs to receive third data sent by the second serial port, instructs the switching circuit to select to receive the third data sent; and the second serial port sends the third data to the second serial port device. Therefore, the first serial port and the second serial port can use corresponding serial port devices in a time division multiplexing manner.