Embodiments of the present invention provide a method and user equipment for feeding back multi-cell channel state information. The method for feeding back multi-cell channel state information includes: feeding back channel state information of a serving cell of a user equipment to a network device; exchanging long-term wideband space state information of a neighboring cell of the user equipment with the network device; feeding back inter-cell additional information of the neighboring cell to the network device, where the inter-cell additional information of the neighboring cell includes a code word that optimizes joint channel information, and the joint channel information is generated according to the channel state information of the serving cell, the long-term wideband space state information of the neighboring cell, and the inter-cell additional information of the neighboring cell.