Abstract: A noise reduction device for ports of DSL filters and a method thereof are revealed. A plurality of signal transmission line sets is arranged at the ports of a DSL filter. A first cross part is formed between the first signal transmission line and the second signal transmission line of the first signal transmission line set. Before the first cross part, the first signal transmission line of the second signal transmission line set is adjacent to the second signal transmission line of the first signal transmission line set while after the first cross part, the first signal transmission line of the second signal transmission line set is adjacent to the first signal transmission line of the first signal transmission line set. Thus the noises induced by interference between two adjacent signal transmission lines cancel each other out. Therefore, no interference noise occurs between two adjacent signal transmission lines.