Disclosed is a method by which a terminal reports channel status information (CSI) to a base station in a wireless communication system, so as to perform a demodulation reference signal (DM-RS)-based downlink transmission through a multi-layer. Particularly, the method comprises the steps of: receiving a channel status information-reference signal (CSI-RS) from the base station; calculating the CSI on the basis of the CSI-RS, on the assumption that a dual pre-coder composed of a first pre-coder and a second pre-coder is applied; and reporting the calculated CSI to the base station, wherein column vectors of the second pre-coder are composed of a single discrete Fourier transform (DFT) vector.