The utility model relates to a specimen clamp for a metallographic premilling machine. The specimen clamp comprises a hand shank and a clamping part, wherein the clamping part is fixedly connected with the hand shank; the clamping part comprises a main clamp body and a secondary clamp body capable of adjusting the distance between the main clamp body and the secondary clamp body; the upper end face of the main clamp body is fixedly connected with the hand shank; a main neck and a secondary neck are respectively formed at the lower end faces of the main clamp body and the secondary clamp body; the main neck and the secondary neck are spliced to form a clamping groove for clamping a specimen. A standard metal specimen is fixed by the specimen clamp, and a to-be-milled surface is exposed; the standard metal specimen can be arranged on a millstone of the pre-milling machine to polish as long as an operator holds the hand shank when the standard metal specimen is polished, so that the direct contact of the hand and the standard metal specimen is avoided, the abrasion on the stress part of the hand caused by friction force can be greatly reduced, and the long-term operation is facilitated.