A method and a device in a node used for wireless communications. A first node receives K first-type reference signals; and transmits a first signal. A transmit power for the first signal is a first power value, a first reference power value is used to determine the first power value, and the first reference power value is linear with a first pathloss. A measurement on a first reference signal is used to determine the first pathloss, the first reference signal being one of the K first-type reference signals; a first index is related to at least a transmission antenna port for the first signal, and is used for determining the first reference signal out of the K first-type reference signals. The method above ensures a more accurate estimation of the interference sidelink transmission has caused to the cellular networks, thus improving the sidelink transmission performance and resource utilization.