Abstract: In this paper, the cell delay in ATM MUX and output-buffered ATM switch is simulated, Which adopts various packet fair queuing algorithms. The simulation results are analyzed, which show that the isolation property of SCFQ(self clocked fair queuing) is weaker than others. If a CBR group has no connection in which traffic exceeds reservation, as to the maximum cell delay and cell average delay, the difference between per_rate_grouping implementation of WF2Q+ and no_per_rate_grouping implementation of WF2Q+ is negligible. According to the results, a scheduling structure dealing with CBR. VBR. ABR and UBR is proposed, which satisfies the strict delay requirement of CBR and guarantees the throughput of VBR. ABR and UBR. The implementation complexity of the scheduler is also discussed.