The invention discloses steel used for nuclear power pressure-bearing equipment and a manufacturing method thereof. The steel comprises the following chemical components by weight: 0.12%-0.18% of C; 0.15%-0.35% of Si; 1.20%-1.65% of Mn; less than or equal to 0.015% of P; less than or equal to 0.010% of S, 0.50%-0.85% of Ni; less than or equal to 0.15% of Cr; 0.020%-0.050% of Al; less than or equal to 0.02% of V; less than or equal to 0.02% of Ti, and the balance Fe and unavoidable impurities. At the same time, non-metallic inclusions in the steel are controlled, and A, B, C and D impurities are guaranteed less than or equal to grade 1.5. The manufacturing method mainly includes steel smelting, rolling, as well as quenching and tempering treatment. Through further optimization of the chemical components, a heat treatment process, and reduction of gas and non-metallic inclusions in steel, the method enables the mechanical properties of a steel plate to be maintained at a high level under a heat treatment state, a simulated post-weld heat treatment state, and a 200DEG C high temperature state, so that the steel plate completely meets the technical index requirements. Meanwhile, the 0DEG C impact absorption energy is still maintained at a high level, and good matching of steel plate strength and toughness is reflected, so that the steel provided in the invention is completely suitable for nuclear power pressure-bearing equipment.