A power allocation method applied to a multi-input multi-output, MIMO, transmission with spatial multiplexing using a plurality of transport layers, wherein the method comprises: receiving, by a terminal device, first downlink control information sent by a network device, wherein the first downlink control information comprises first power allocation information for a plurality of transport layers; determining, by the terminal device, a first transmit power of each of the plurality of transport layers based on the first power allocation information; and sending, by the terminal device, first uplink data based on the first transmit power of each transport layer; wherein before the sending first uplink data to the network device, the method further comprises: determining, by the terminal device, inter-layer power allocation capability information supported by each transport layer, wherein the first uplink data comprises the inter-layer power allocation capability information, and the inter-layer power allocation capability information is used to determine second power allocation information for the plurality of transport layers; wherein after the sending first uplink data to the network device, the method further comprises: receiving, by the terminal device, second downlink control information sent by the network device, wherein the second downlink control information comprises the second power allocation information for the plurality of transport layers; determining, by the terminal device, a second transmit power of each of the plurality of transport layers based on the second power allocation information; and sending, by the terminal device, second uplink data based on the second transmit power of each transport layer, wherein the PMI or the SRI in the first downlink control information is the same as a PMI or an SRI in the second downlink control information. receiving, by a terminal device, first downlink control information sent by a network device, wherein the first downlink control information comprises first power allocation information for a plurality of transport layers; determining, by the terminal device, a first transmit power of each of the plurality of transport layers based on the first power allocation information; and sending, by the terminal device, first uplink data based on the first transmit power of each transport layer; wherein before the sending first uplink data to the network device, the method further comprises: determining, by the terminal device, inter-layer power allocation capability information supported by each transport layer, wherein the first uplink data comprises the inter-layer power allocation capability information, and the inter-layer power allocation capability information is used to determine second power allocation information for the plurality of transport layers; wherein after the sending first uplink data to the network device, the method further comprises: receiving, by the terminal device, second downlink control information sent by the network device, wherein the second downlink control information comprises the second power allocation information for the plurality of transport layers; determining, by the terminal device, a second transmit power of each of the plurality of transport layers based on the second power allocation information; and sending, by the terminal device, second uplink data based on the second transmit power of each transport layer, wherein the PMI or the SRI in the first downlink control information is the same as a PMI or an SRI in the second downlink control information. determining, by the terminal device, inter-layer power allocation capability information supported by each transport layer, wherein the first uplink data comprises the inter-layer power allocation capability information, and the inter-layer power allocation capability information is used to determine second power allocation information for the plurality of transport layers; wherein after the sending first uplink data to the network device, the method further comprises: receiving, by the terminal device, second downlink control information sent by the network device, wherein the second downlink control information comprises the second power allocation information for the plurality of transport layers; determining, by the terminal device, a second transmit power of each of the plurality of transport layers based on the second power allocation information; and sending, by the terminal device, second uplink data based on the second transmit power of each transport layer, wherein the PMI or the SRI in the first downlink control information is the same as a PMI or an SRI in the second downlink control information. receiving, by the terminal device, second downlink control information sent by the network device, wherein the second downlink control information comprises the second power allocation information for the plurality of transport layers; determining, by the terminal device, a second transmit power of each of the plurality of transport layers based on the second power allocation information; and sending, by the terminal device, second uplink data based on the second transmit power of each transport layer, wherein the PMI or the SRI in the first downlink control information is the same as a PMI or an SRI in the second downlink control information.