A power control method and a power control device for terminal device-to-device communications, and a parameter transmission method includes: determining at least one terminal which is outside a base station coverage range and interferes with a base station; acquiring, by the base station, signal strength information about a measurement signal sent by each terminal of the at least one terminal when the measurement signal reaches the base station, and configuring a corresponding power control parameter for each terminal according to the signal strength information; and sending, by the base station, the corresponding power control parameter of each terminal to a synchronization source terminal within the base station coverage range corresponding to each terminal, so as to send the power control parameter to a corresponding terminal by the synchronization source terminal, so that each terminal conducts power control using the corresponding power control parameter.