The invention discloses a method for inwardly processing an oil passage hole by an inner valve type hydraulic breaking hammer. The method processes the hole by adopting the following processing steps: a. three main oil passages of a middle cylinder body are drilled to required sizes; b. a piston hole and a reversing valve hole are processed; c. a position on which an inner transverse oil passage hole needs to be processed is marked ; and d. numerical control electromachining equipment is used for processing the transverse oil passage hole on the marked position towards the direction of an oil through hole. Compared with the prior art, the oil passage hole processed by the technology has the advantages of simple technology and low processing cost, and can thoroughly solve the quality problem of oil seepage on the surface of the cylinder body.