A channel controlling device includes: a multiplexing circuit coupled to a plurality of channels for selecting a specific channel from the channels to output a channel data according to a selecting signal, wherein the channels correspond to a plurality of predetermined digital numbers; a sorting circuit arranged to queue the predetermined digital numbers to form a plurality of queued digital numbers according to a data output order of the channels; and an arbitration circuit, arranged to determine the selecting signal according to the plurality of queued digital numbers.