To simultaneously support guaranteed real-time services and best-effort service, a Priority-based Scheduling Architecture (PSA) designed for high-speed switches is proposed. PSA divides packet scheduling into high-priority phase and low-priority phase. In the high-priority phase, an improved sorted-priority algorithm is presented. It introduces a new constraint into the scheduling discipline to overcome bandwidth preemption. Meanwhile, the virtual time function with a control factor α is employed. Both computer simulation results and theoretic analysis show that the PSA mechanism has excellent performance in terms of the implementation complexity, fairness and delay properties.