A method for detecting back-drilled holes in a PCB and a PCB panel are provided. The method comprises: forming, on a metal layer of a first inner layer of a multi-layer PCB, metal rings according to positions of the back-drilled holes during a process of forming the PCB, wherein each of the formed metal rings has an outer diameter greater than an aperture of each of the back-drilled holes; forming, at positions corresponding to the positions of the back-drilled holes, metal holes extending through an outer layer of the PCB and the formed metal rings; forming two first detection holes electrically connected with the formed metal rings; forming the back-drilling holes on the PCB, which extend through and expand the metal holes; and detecting an electrical conduction between the two first detection holes so as to determine whether a position offset exists between the back-drilled holes and the metal holes.