This application provides a power control method and a power control apparatus. The method includes: sending, by a first terminal device, a first signal to a second terminal device at a first transmit power; receiving, by the first terminal device, first information from the second terminal device, where the first information is used to indicate or includes a first received power, and the first received power is a received power of the first signal; determining, by the first terminal device, an estimated value of a path loss between the first terminal device and the second terminal device based on the first transmit power and the first received power. According to this application, power control can be properly performed. This application may be applied to an internet of vehicles, for example, V2X, LTE-V, and V2V, or may be applied to fields such as D2D, intelligent driving, and intelligent connected vehicles.