Printed circuit board and common-mode filter thereof

The invention relates to a printed circuit board, which comprises a signal layer and a grounding layer close to the signal layer; a pair of difference transmission lines is arranged on the signal layer; a common-mode filter is arranged on the grounding layer and comprises two filtering parts positioned on the two sides of the difference transmission lines projected on the grounding layer; each filtering part is formed by connecting a plurality of mutually-parallel strip copper foils in an end-to-end manner at intervals; and a hollow area on the two filtering parts is communicated with a strip hollow area. The common-mode filter is applied to the printed circuit board, and a common-mode signal running through the difference transmission lines can be effectively filtered out.