The invention discloses a high-homogeneous large-size ultrahigh-strength steel bar comprising the chemical composition by the mass percentage: 0.25-0.40% of C, 0.50-1.50% of Mn, 1.20-2.50% of Si, 0.80-1.20% of Cr, 4.50-6.50% of Ni, 0.40-1.00% of Mo, not more than 0.35% of V, not more than 0.20 % of Nb, not more than 0.005% of S, not more than 0.01% of P, not more than 20 ppm of O, not more than 25 ppm of N, and the balance Fe. At the same time, a production method of the steel bar is also provided; the forging process includes steel ingot heating, first upsetting and stretching, second upsetting and stretching, third upsetting and stretching, and stretching. The high-homogeneous large-size ultrahigh-strength steel bar has excellent mechanical properties; macrostructures comprise that white spots, dark spots, radial segregation and annual ring-shaped segregation all reach an AAAA level, the transverse performance reaches more than 90% of the longitudinal performance and a homogenization effect is achieved.