The invention particularly discloses a machining process of a tool bit-replaceable deep hole drill, and belongs to the technical field of drill bit production and machining. The process is to perform heat treatment and machining of a chip removing groove in sequence; a high-temperature machining link in the heat treatment adopts a gradual mode; the local high-temperature treatment is performed one section by one section, and the overall high-temperature treatment is not performed, so that the prevention of deformation of slender workpieces is facilitated; and in addition, the chip removing groove is machined by a grinding mode, so that the machining efficiency is improved, and the machining of the deep hole drill with large time diameter and longer length is facilitated.