The method includes: A first terminal device determines a transmit power of a data channel, wherein the transmit power of the data channel comprise a first data channel part and a transmit power of a second data channel part, where the first data channel part is a part of the data channel that has a same time domain resource with a control channel, and the second data channel part is another part of the data channel that has a different time domain resource with the control channel. The first terminal device sends data in the first data channel part at the transmit power of the first data channel part, and sends data in the second data channel part at the transmit power of the second data channel part. This application may be applied to internet of vehicles, for example, V2X, LTE-V, and V2V.