Integrally formed compound milling cutter

The invention discloses an integrally formed compound milling cutter comprising a holder of which the lower end is provided with a cutter body. The lower end of the cutter body is provided with a first cutter head used for milling and chamfering small holes, and the transition position of the lower end and the side wall of the cutter body is provided with a second cutter head used for milling bigholes; and a third cutter head used for milling and chamfering the big holes is formed at the upper end of the cutter body. According to the milling cutter disclosed by the invention, a first cuttingedge, a second cutting edge and a third cutting edge of are integrally formed, so that hole grooves of different sizes can be formed by machining with no need of replacing blades of different sizes, and the working procedures are simplified; the production efficiency is improved, and the big holes can be formed by machining and the chamfering of the small holes is achieved while milling the big holes; the phenomena of burr