A multi-antenna data transmission method for performing two-level CSI measurement, the method comprising: receiving, by a terminal device, downlink control signaling sent by a network device, wherein the downlink control signaling instructs the terminal device to feed back statistical channel parameter information to the network device, wherein the downlink control signaling is further used to instruct the terminal device to feed back instantaneous channel parameter information to the network device; determining, by the terminal device, the statistical channel parameter information according to statistical channel information that is obtained by means of computation after the terminal device measures a plurality of instantaneous channels based on a level-one reference signal sent by the network device; and feeding back, by the terminal device, the statistical channel parameter information to the network device according to the downlink control signaling, determining, by the terminal device, the instantaneous channel parameter information according to instantaneous channel information that is obtained by means of measurement performed by the terminal device on an instantaneous channel, comprising: measuring, by the terminal device, the instantaneous channel according to a precoded level-two RS, reference signal, sent by the network device, to obtain the instantaneous channel information, wherein the precoded level-two RS is determined by the network device by precoding the level-two RS according to the statistical channel parameter information; and performing, by the terminal device, quantization processing on the instantaneous channel information to determine the instantaneous channel parameter information; and feeding back, by the terminal device, the instantaneous channel parameter information to the network device according to the downlink control signaling. receiving, by a terminal device, downlink control signaling sent by a network device, wherein the downlink control signaling instructs the terminal device to feed back statistical channel parameter information to the network device, wherein the downlink control signaling is further used to instruct the terminal device to feed back instantaneous channel parameter information to the network device; determining, by the terminal device, the statistical channel parameter information according to statistical channel information that is obtained by means of computation after the terminal device measures a plurality of instantaneous channels based on a level-one reference signal sent by the network device; and feeding back, by the terminal device, the statistical channel parameter information to the network device according to the downlink control signaling, determining, by the terminal device, the instantaneous channel parameter information according to instantaneous channel information that is obtained by means of measurement performed by the terminal device on an instantaneous channel, comprising: measuring, by the terminal device, the instantaneous channel according to a precoded level-two RS, reference signal, sent by the network device, to obtain the instantaneous channel information, wherein the precoded level-two RS is determined by the network device by precoding the level-two RS according to the statistical channel parameter information; and performing, by the terminal device, quantization processing on the instantaneous channel information to determine the instantaneous channel parameter information; and feeding back, by the terminal device, the instantaneous channel parameter information to the network device according to the downlink control signaling.