A method and apparatus for carrier aggregation communication system

Embodiments of the present invention provides a method of communication for carrier aggregation system, relates to communication technologies, in order to effectively guarantee the normal communication base station and the user equipment to the invention. The communication method comprising: receiving a base station through a physical downlink shared channel PDSCH subframe information delivered by the secondary cell n; If the primary cell subframe is a downlink subframe n: the primary cell in the sub-frame or subframe m p be sent on the PDSCH information at ACK / NACK feedback, wherein m is the ACK / NACK corresponding to subframe n timing relationship according to the primary cell, the primary cell of the primary sub-cell feedback ACK / NACK of the subframe index of a subframe of frame n PDSCH, p is in accordance with the ACK / NACK corresponding to subframe n timing relationship of the secondary cell, the secondary cell in the secondary cell feedback subframe n a PDSCH ACK / NACK of the subframe index of a subframe. The present invention can be used in a carrier aggregation system.