||The continuous growth of network communication has been increasing the demands for high transmission capacity and quality of services (QoS) in networks. Optical networks are believed to solve the high transmission capacity problem in low cost with wavelength division multiplexing (WDM). However, no practical optical random access memory (RAM) makes buffering in switching a challenging problem. Many researches have been performed on the design of an optical switch with buffer using optical fiber delay lines together with switching fabrics. A switch for real network use should have the ability to handle bursty traffic and support QoS. However, most of the designs in literature are satisfactory for some aspects only. The thesis is focused on the design of an optical packet switch, which is practical in real networks. Through reviewing some designs in literature, it is found that a type of multistage feed-forward output buffering switch can be implemented through utilizing WDM such that it has packet drops only when buffer overflows under FIFO (first-in first-out) queueing discipline. Therefore, it likes SLOB, a switch proposed in another literature, that it can handle bursty traffic. The change from feed-forward to inter-connected stages architecture is done to adapt multi-classes switching and results in the switch proposed in this thesis. With the designed scheduling algorithm, the ability for handling bursty traffic with FIFO queueing discipline is kept. Simulations have been performed to study the ability of the proposed switch in QoS. It can be concluded that its internal congestion free property for FIFO queueing discipline allows a low packet loss rate for multi-classes switching when the difference of proportions of packets between different classes is large. When comparing with some other designs, the proposed switch shows its potential for real network use with the advantages in bursty traffic and QoS.