The invention discloses a pass system for rolling round steel and relates to the technical field of steel rolling pass. The pass system used by a roughing rolling unit is a box-square-oval-round pass system, wherein rolling mills equipped with box pass and oval pass are vertical rolling mills; and rolling mills equipped with square pass and round pass are horizontal rolling mills. Compared with the prior art, the pass system disclosed by the invention has the advantages that oval holes are formed through the vertical rolling mill, and round holes are formed through the horizontal rolling mill, so that the process of twisting rolling is eliminated, the pass system for rolling the round steel without twisting rolling is formed, a round steel finished product is rolled by the horizontal rolling mills, and an oval rolled piece is not required to be twisted, so that rolling of the round steel is facilitated, therefore, the product quality is improved.