The present application discloses a method for D2D communication and a terminal device, the method including: receiving, sidelink control information (SCI) transmitted by a second terminal device; determining, by the first terminal device, that the SCI is in a first format or in a second format, where the SCI includes a resource reservation bit, and the resource reservation bit in the SCI of the first format is not used to indicate whether the second terminal device reserves a time-frequency resource for next data transmission, and the resource reservation bit in the SCI of the second format is used to indicate whether the second terminal device reserves the time-frequency resource for the next data transmission; and prohibiting data transmission on a plurality of the time-frequency resources distributed in accordance with a first time period if the first terminal device determines that the SCI is in the first format.