The invention discloses a special high-effect brake for machining. The special high-effect brake for machining comprises an oil cylinder, pistons and a brake disc, wherein the brake disc is arranged under the right side of a fixed support; a brake inlay is arranged above the fixed support; the oil cylinder is arranged in the middle of the inner part of the brake inlay; an unloading valve is arranged on the left side of the brake inlay; an oil inlet is formed in the middle of the left side of the unloading valve; and the pistons are arranged on the left side and the right side under the oil cylinder. The special high-effect brake for machining provided by the invention has the beneficial effects that the special high-effect brake for machining is scientific and reasonable in structure; theunloading valve is arranged on the oil cylinder, so that hydraulic oil in the oil cylinder can be prevented from flowing backwards, oil supply for a hydraulic system is maintained, the effect of the brake is improved, and the problem that oil pressure required for promoting a pipeline is not big enough is solved; and in addition, a dust cover is arranged on each piston, so that the problem that dust enters the pistons so as to influence the brake effect is solved, and the brake is convenient to use.