The application relates to radio communications and discloses a method and apparatus for feeding back and receiving acknowledgment (ACK) information of semi-persistent scheduling (SPS) data packets. The method includes receiving downlink data packets and an uplink data assignment indicator (UL DAI) from a base station, wherein a value of the UL DAI indicates a number (N) of all scheduled downlink sub-frames which scheduled by the base station for the user equipment, the number N is greater than 1, and a number k (k