A circuit board and a manufacturing method thereof are provided. According to the method, a dielectric layer is formed on a dielectric substrate, and the dielectric layer contains active particles. A surface treatment is performed on a surface of the dielectric first conductive layer is formed on the activated surface of the dielectric layer. A conductive via is formed in the dielectric substrate and the dielectric layer. A patterned mask layer is formed on the first conductive layer, in which the patterned mask layer exposes the conductive via and a part of the first conductive layer. A second conductive layer is formed on the first conductive layer and conductive via exposed by the patterned mask layer. The patterned mask layer and the first conductive layer below the patterned mask layer are removed.