A method for transmitting a Channel State Information (CSI) reporting at a user equipment (UE) in a wireless communication system is disclosed. The method includes transmitting a rank indicator (RI) and a first type precoding matrix indicator (PMI) to a base station (BS) according to a first CSI feedback type; transmitting a second type PMI to the BS according to a second CSI feedback type, wherein the RI and the first type PMI are jointly coded, and transmitted through a physical uplink control channel (PUCCH), wherein the RI and the second type PMI are not jointly coded, and transmitted through the PUCCH, wherein a transmission period of the first type PMI is different than a transmission period of the second type PMI, wherein the transmission period of the first type PMI is longer than the transmission period of the second type PMI, and wherein the RI is 2, 3 or 4 bits, and a size of the jointly coded RI and the first type PMI are 4 bits.