The utility model relates to a fixture for boring holes of a small box. The fixture comprises a base, and four posts, wherein the bottom surface of the base is processed into a reference plane; the four posts are positioned at four corners of the base and connected with the base; and at least one pair of transverse and horizontal bolt mandrils are respectively connected with the four posts through threads. The post can be selected in shape of angle steel section, and the transverse and the longitudinal bolt mandrils are respectively connected with two edge plates vertical to the posts through threads. While the fixture bores holes on the small box, the box to be processed is disposed in the fixture, the bolt mandrils on the posts are screwed and tightly press against each side of the box so as to clamp and fix the box, and the box to be processed as well as the fixture is arranged on a rotary workbench of a boring machine and is subjected to boring with respect to the bottom surface of the fixture as an accuracy reference plane, thereby achieving the requirement for dimension tolerance, coaxiality and verticality of each shaft hole. The fixture can conveniently bore holes on the small box, and has the advantages of high efficiency and low cost while meeting the processing requirement.