A digital-to-analog converter includes a first input end for reversely receiving a digital signal, a second input end for receiving multiple reference voltages arranged in a best order, wherein the best order is determined by reordering an initial order several times, multiple first switches coupled to each other stage by stage like a tree for selecting one of the reference voltages to be a first selection result, multiple second switches coupled in series for selecting one of the reference voltages to be a second selection result.