The present invention relates to a wireless communication system. A method for user equipment transmitting channel state information (CSI) in the wireless communication system, according to the present invention, comprises the steps of: receiving information on an N number of CSI configurations for reporting the CSI; receiving information for selecting an M (2≦M≦N) number of the CSI configurations for joint CSI from the N number of the CSI configurations; calculating the M number of rank indexes (RI) based on each channel corresponding to the M number of CSI configurations; calculating a joint RI based on a synthetic channel generated by synthesizing the channels corresponding to the M number of the CSI configurations; and transmitting information on whether to report the joint CSI based on a result from comparing the M number of the RIs and the joint RI.