As the demands on quality of service (QoS) of real-time applications over the Internet increase, many research efforts have developed various packet scheduling schemes to support differentiated services. In this paper, we propose a new multi-level packet scheduling algorithm, MLDDRR, enhanced from the existing dynamic deficit round-robin (DDRR) for the support of delay-sensitive applications. The network operator can simply change the level of service differentiation by adjusting parameters. The MLDDRR can achieve high throughput efficiently and simultaneously provide smaller delay for short packets of each service class. The feature of small delay for short packets is of great importance for improving the playback quality of real-time applications such as VoIP or scalable media stream delivery. Simulation results showing the high effectiveness and small overhead of MLDDRR are also presented.