Disclosed are a power control method and device for D2D transmission. The method includes determining an upper limit value of interference power corresponding to a terminal. The upper limit value of the interference power is the maximum interference value which is allowed by a base station and generated by D2D transmission to cellular transmission. The base station sending the upper limit value of the interference power to the terminal the terminal determines the upper limit value of D2D transmission power by using the upper limit value of the interference power. The terminal determines the upper limit value of the D2D transmission power, and determines the D2D transmission power, the D2D transmission power of the terminal device can be controlled, transmitting power of the D2D transmission is controlled to make the interference generated by same to the cellular transmission to a controlled range, and the interference of a D2D signal to a cellular signal is controlled.