The invention discloses a preparation method of ultrahigh-strength high-
plasticity hot stamping forming steel, and belongs to the technical field of automobile steel. The steel comprises the following chemical components of, in percentage by
mass, 0.30%-0.55% of C, 1.0%-2.5% of Si, 1.0%-3.0% of Mn, 0.5%-2.0% of Cr, 0.05%-2.0% of Ni, 0.01%-0.10% of Al, 0.04%-0.15% of Nb, less than or equal to 0.5% of Mo, less than or equal to 0.08% of RE, less than 0.015% of P, less than 0.015% of S, less than or equal to 1.0% of Cu or less than or equal to 0.06% of V, or the combination of the two, and the balance of Fe and inevitable
impurity elements, and Si+Mn+Cr is larger than or equal to 3.5% and less than or equal to 5.5%; and automobile parts are obtained through the steps of
smelting, pouring solidification, hot rolling, acid
pickling, cold rolling, annealing,
hot stamping forming and the like. The preparation process of the hot forming steel part is simple, and the structure obtained after
hot stamping forming is a
martensite matrix and 1.5%-7.0% of retained
austenite; and after the components are optimized, it can be guaranteed that the tensile strength of parts is larger than or equal to 2200 MPa, the yield strength is larger than or equal to 1300 MPa, the total elongation is larger than or equal to 9.0%, and the steel is suitable for
automobile safety parts and other high-strength-
toughness parts and has very important significance on achieving high
toughness and light weight of automobiles.