A multi-antenna data transmission method, network device, terminal device, and system is suggested to effectively increase a system throughput. The method includes: sending, by a network device, downlink control signaling to a terminal device, where the downlink control signaling instructs the terminal device to feed back statistical channel parameter information, the statistical channel parameter information is determined by the terminal device according to statistical channel information, and the statistical channel information is obtained after the terminal device measures instantaneous channels many times; receiving, by the network device, the statistical channel parameter information that is determined according to the downlink control signaling and that is sent by the terminal device; and processing, by the network device, downlink data according to the statistical channel parameter information, and sending processed downlink data to the terminal device.