A base station device, user equipment, and a method for reporting channel state information are disclosed. The base station device receives at least one piece of aperiodic channel state information (CSI) from user equipment, where the at least one piece of aperiodic CSI corresponds to an aperiodic CSI measurement result on a first reference subframe, the aperiodic CSI measurement result on the first reference subframe is an aperiodic CSI measurement result of a first downlink subframe set, and the first reference subframe is a subframe in the first downlink subframe set. The base station device effectively receives an aperiodic channel state measurement result of the downlink subframe set.