The invention provides normalized high-strength low-yield-ratio
pressure vessel steel with the temperature of minus 70 DEG C. The normalized high-strength low-yield-ratio
pressure vessel steel with the temperature of minus 70 DEG C comprises, by
mass percentage, 0.10-0.20 of C, not larger than 0.10 of Si, 1.00-2.00 of Mn, not larger than 0.010 of P, not larger than 0.002 of S, 0.005-0.050 of Alt,not larger than 0.50 of Cu, not larger than 0.50 of Cr, not larger than 0.50 of Mo, 0.01-0.05 of Nb, 0.02-0.06 of V, 0.50-1.00 of Ni, not larger than 0.004 of N and the balance Fe and unavoidable inclusions, wherein Cu, Cr, and Mo satisfy the condition that, by
mass percentage, the sum of [Cu], [Cr] and [Mo] is larger than or equal to 0.40 and smaller than or equal to 0.90. By the adoption of thenormalized high-strength low-yield-ratio
pressure vessel steel with the temperature of minus 70 DEG C and a manufacturing method of the normalized high-strength low-yield-ratio pressure vessel steel with the temperature of minus 70 DEG C, through composition design,
inclusion control, rolling and heat treatment, the steel is high in strength, high in low-temperature obdurability and low in
yield ratio and can be used for manufacturing various low-temperature movable pressure vessels.