The invention discloses a low-alloy high-strength high-impact-energy extra-large special-shaped ring forging. Low-alloy high-strength steel comprises, by weight, 0.08-0.12% of C, 0.5-0.6% of Mn, lessthan or equal to 0.006% of P, less than or equal to 0.006% of S, 0.5-0.65% of Si, 1.4-1.5% of Cr, 0. 55-0.65% of Mo, 0.1-0.2% of Ni, less than or equal to 0.15% of Cu, less than or equal to 0.04% of V, 0.03-0.04% of Nb, 0.02-0.04% of Al, less than or equal to 0.01% of Sn, less than or equal to 0.01% of As, less than or equal to 0.0012% of Sb and the balance Fe and impurities, then through nozzle cold sawing, riser collection, riser heat chopping, then three times of upsetting and two times drawing, broaching chambering, special-shaped ring rolling, preparatory heat treatment, rough turning, sawing, preheating and arc finishing. In this way, chemical compositions of raw materials are optimized, a reasonable matching heat treatment system is adopted, the stability of the impact work can be improved through maximum simulated post-weld heat treatment of the materials, the product once inspection pass rate is increased to 100%, energy waste caused by rework and repair is avoided, the production cycle is shortened, the manufacturing cost is reduced, and the competitiveness of enterprises is improved.