The invention relates to a steel forging with an ultra-high strength and an ultra-high low-temperature impact on the box body of a fracturing pump valve and a manufacturing method of the steel forging. The steel forging is used for solving the technical problems of low mechanical performance, bad corrosion resistance, short service life, and high cost of the existing steel materials. The steel forging comprises the following chemical ingredients in percentage by weight: 0.25-0.3% of C, 0.15-0.35% of Si, 0.6-0.9% of Mn, 1.8-2.2% of Cr, 4.05-4.25% of Ni, 0.46-0.6% of Mo, 0.12-0.18% of V, not greater than 0.01% of P, not greater than 0.01% of S, not greater than 0.12% of Nb, not greater than 0.12% of Re, not greater than 0.2% of Cu, not greater than 0.00016% of H, not greater than 0.0035% of O, not greater than 0.0065% of N, and the balance of Fe and inevitable impurities. The steel forging disclosed by the invention can be used in the fields of petroleum exploitation and shale gas exploitation.