The invention discloses a steel with high plasticity, high toughness and high strength and a manufacturing method thereof. The chemical compositions of the steel are as follows in terms of weigh percentage: 0.15 to 0.30 of C, 0.20 to 1.40 of Mn, 0.10 to 0.50 of Si, less than or equal to 0.015 of P, less than or equal to 0.012 of S, less than or equal to 0.20 of Ni, 0.40 to 1.50 of Cr, 0.25 to 1.35 of Mo, 0 to 0.10 of V, less than or equal to 0.2 of Cu, 0.01 to 0.05 of Al, 0.0005 to 0.0020 of B, less than or equal to 0.010 of (O+N) and the balance of Fe and impurities. The manufacturing method comprises the following steps: smelting according to the formula, continuous casting into a blank, hot rolling into plates or tubes, quenching at the temperature of 875 to 930 DEG C and holding the temperature for 25 to 40 minutes, tempering at the temperature of 625 to 675 DEG C for 30 to 90 minutes, then air cooling, and quenching and tempering heat treatment. The steel has yield strength of more than or equal to 1000MPa, tensile strength of more than or equal to 1100MPa, zero-degree-centigrade charpy impact work of more than or equal to 100J, specific elongation of 20 to 30 percent and is applicable to manufacture important structures of engineering machinery, high buildings and oil well pipes, and the like.