The invention relates to a circuit board and a drilling method of the circuit board. The circuit board is drilled to form the first hole, the hole
diameter of the first hole is smaller than that of the target hole, and when the second hole is drilled, a part of material is
cut by drilling the first hole, so that the
chip removal requirement for drilling the second hole is reduced; meanwhile, as the drilling area of the first hole is located in the drilling area of the second hole, the hole wall of the first hole can be used for providing supporting and guiding effects for drilling of the second hole, and the breaking risk of the
drill bit is reduced. Due to the fact that the hole depth of the first hole is smaller than that of the target hole, the
chip removal requirement for drilling thefirst hole and the blade length requirement of the
drill bit are lowered, and the problem that in the process of drilling the first hole, the
drill bit is broken due to the large drilling depth or
chip removal problem of the
drill bit is effectively solved. According to the drilling method of the circuit board, especially in the
machining process of the circuit board with the high thickness-
diameter ratio, the target hole can be formed only through two drilling steps, the drilling steps are simplified, the drilling efficiency is improved, and the production efficiency of the circuit board is improved.