The invention relates to steel for 20 control Cr nuclear power and a production method thereof. The steel comprises the following chemical components in percentage by weight: 0.17-0.25 percent of C, 0.4-1.0 percent of Mn, 0.18-0.25 percent of Si, 0.18-0.30 percent of Cr, not more than 0.005 percent of S, 0.020-0.040 percent of Alt, not more than 0.015 percent of P and the balance of Fe and inevitable impurities. The production method comprises the following steps of: pouring the designed and smelt molten steel according to the chemical components into a thick plate billet with 220-250mm; heating the plate billet in a heating furnace at the temperature of 1,150-1,250DEG C for 3-5h; discharging from the furnace and rolling at two stages; and carrying out the normalizing treatment. The produced product has the yield strength of 350MPa, the tensile strength of 480MPa, the elongation percentage of 25 percent, the high-temperature stretching yield strength of 250MPa, a transverse impact mean value at -30DEG C of 100J and favorable cold bending performance. The invention has the advantages of simplified work procedures, cost saving and favorable high-temperature stretching performance; and the product is applied to the nuclear power project and is steel for a nuclear power pipe fitting in the high-temperature turbulent state.