The invention provides a high-precision bar rolling mill. The high-precision bar rolling mill comprises a base and a roller system. The roller system and the base are mounted and fixed through a roller system support. A conical hole and four grooves are formed in each stand column of the base of the rolling mill. Adjusting liner plates are arranged in the grooves. Vertical boss structures matched with the four grooves in each stand column of the base of the rolling mill are arranged on the four sides of the roller system support. An assembly gap between the roller system support and the stand columns of the base can be adjusted by tightly pressing screws through the adjusting liner plates. Semi-conical holes are formed in the middles of bosses of the roller system support and matched with the conical holes in the stand columns of the base of the rolling mill. The roller system support and the base of the rolling mill are locked through conical drift bolts. The high-precision bar rolling mill is compact in structure, easy to dismount and mount, high in rigidity, small in bounce value and free of axial displacement; round bar products rolled through the high-precision bar rolling mill are high in section size precision, small in ovality and especially suitable for production of bars; and domestication and batch manufacturing of the high-precision bar rolling mill can completely replace an import mode, and great economic and social benefits are achieved.