A power control method and a terminal device are disclosed. The method includes: sending, by a first terminal device, first data and first sidelink control information corresponding to the first data to at least one second terminal device; receiving, by the first terminal device, at least one piece of power adjustment information from the at least one second terminal device, where the at least one piece of power adjustment information is determined by the at least one second terminal device based on at least one of the first data and the first sidelink control information; determining, by the first terminal device, a transmit power for second data based on the at least one piece of power adjustment information; and sending, by the first terminal device, the second data to the at least one second terminal device at the transmit power.