Abstract: A method of forming measuring targets for measuring the dimensions of a substrate during a substrate manufacturing process is provided. First, a board having a base layer and a conductive layer is provided, wherein the conductive layer is disposed on a surface of the base layer. Then, at least one through hole is formed in the board as a measuring target for measuring the dimensions of the substrate. Next, a plated via is formed in the through hole as another measuring target for measuring the dimensions of the substrate. Thereafter, a patterned dielectric layer is formed on the board to expose the plated via as a next measuring target for measuring the dimensions of the substrate. In the present invention, measuring targets are formed during a substrate manufacturing process and the dimensions of the substrate are measured instantly. The accuracy in process alignment is improved without increasing the fabrication cost.