Disclosed is a millimeter-wave communication spatial multiplexing transmission method, and the method includes: a millimeter-wave communication device initiating high-speed data communication with a target device, sending a beamforming request to the target device via a low frequency band communication module, if the millimeter-wave communication device has received an acknowledgement response sent by the target device via the low-frequency band communication module and learns that a non-target device is performing the high-speed data communication in a same frequency band with the high-speed data communication initiated by the millimeter-wave communication device, the millimeter-wave communication device configuring transmitting power which is less than default power to perform beam scanning.