A bandwidth arranging method includes the following steps of: registering isochronous packets of N isochronous streams, N is a natural number greater than 1; segmenting an isochronous transmission period into M sub-periods, M is a natural number greater than 1; arranging operation of transmitting each of the N isochronous streams in one of the M sub-periods and allocating corresponding bandwidth according to bandwidth requirement information corresponding to each of the N isochronous streams; arranging the isochronous packets into M output queues corresponding to the respective M sub-periods; outputting isochronous packets stored in the M output queues in the respective M sub-periods.