In orthogonal frequency division multiple access (OFDMA)-based systems, base station (BS) can adaptively adjust modulation and coding parameters according to channel quality indicator (CQI) fed back, therefore spectrum efficiency can be significantly improved. In this paper, based on the joint consideration of both quality of service (QoS) difference and spectrum efficiency, we have proposed a novel resource allocation algorithm and a modified top-M feedback scheme for OFDMA-based systems with limited CQI feedback. In order to meet the QoS requirements, users of different traffic types are assigned with different priorities. Simulation results have proved that the proposed allocation algorithm can fully sustain user's requirements under reasonable traffic loads, and simultaneously the feedback load can be greatly reduced.