Disclosed is a time-division multiplexing (TDM) scheduler capable of determining a service order for serving N packet transmission requesters. The TDM scheduler includes: N current count value generators configured to serve the N packet transmission requesters respectively, and generate N current count values according to parameters of the N packet transmission requesters, a previous scheduling result generated by the EDD scheduler previously, and a predetermined counting rule; and an earliest due date (EDD) scheduler configured to generate a current scheduling result for determining the service order according to the N current count values and a predetermined urgency decision rule, wherein an extremum of the N current count values relates to one of the N packet transmission requesters, and the EDD scheduler selects this requester as the one to be served preferentially.