Packet scheduling algorithm controls the order of packet service, which is crucial in the design of a QoS network. In this paper, the authors first give a virtualclock difference-bounded framework (VDBF), then present a new scheduling algorithm——DFQR (difference-based fair queueing by re-calibration), in which they use a hierarchical structure, recalibrate the system virtual clock periodically, compromise network delay with fairness and implementation complexity. Finally, they demonstrate the performance benefit of DFQR by analysis and simulation.