The invention discloses a method and a device for feeding back channel state information. The method comprises the following steps of: determining the channel state information by user equipment (UE), wherein the channel state information comprises any combination of rank indicator (RI) information, channel quality indication (CQI) information and precoding matrix indicator (PMI) information; and regularly returning the determined channel state information to a base station through a physical upstream control channel (PUCCH), wherein the PMI information possibly comprises i1 and i2. The invention provides a technical scheme for feeding back the channel state information in a long term evolution advanced (LTE-A) system, and ensures the normality of channel state information feedback. Furthermore, even though the RI information or RI and i1 combined coding information is lost, normal feedback of the channel state information is ensured by the method, so the normal operation of a communication system is ensured.