The present disclosure provides a reference signal transmission method, a reference signal transmission device, a base station and a user equipment. The transmission method of the present disclosure includes: implicitly or explicitly indicating to a user equipment (UE), position information of a target subcarrier for mapping a target phase tracking reference signal (PTRS) port, among subcarriers occupied by a target demodulation reference signal (DMRS) port. The target DMRS port is a DMRS port associated with the target PTRS port.