The invention relates to the technical field of printed circuit boards, in particular to a manufacturing method for circuit board back hole drilling. According to the method of the invention, a copperlayer with a thickness smaller than or equal to 10 micrometers is electroplated in a whole-plate electroplating process; compared with a method which electroplates a copper layer at one time to meetthe design requirement of a final product, the method of the invention enables the hole diameter of a first through hole is relatively large during back drilling, and therefore, drilling slag can be guided out from the first through hole, and the amount of drilling slag formed during the back drilling can be reduced, especially, the amount of copper drilling slag can be decreased; the granularityof the copper drilling slag is small, hole blocking caused by large-particle copper drilling slag can be avoided; the copper drilling slag remaining in the hole can be completely removed during alkaline etching, and therefore, a hole blocking risk is reduced, and a reliability hidden danger in the aspect of circuit conduction caused by the fact that the copper drilling slag remains in the hole canbe eliminated. Especially for a first through hole with the hole diameter of 0.15 mm, the thickness of the hole wall copper of the through hole, which is formed by electroless plating copper and whole-board electroplating is controlled to be 5 microns, and a hole blocking phenomenon is avoided, and the problem of hole blocking during the back drilling is completely solved.