Steel plate and preparation method thereof

The invention discloses a steel plate and a preparation method thereof, and the steel plate comprises the following chemical elements in percentage by mass: 0.15-0.22% of C; 0.10% to 0.30% of Si; 0.80% to 1.60% of Mn; 0.20% to 0.70% of Cr; 0.10% to 0.60% of Mo; 0.020% to 0.050% of Nb; v, the content of the raw materials is 0.020%-0.060% Ti < = 0.008%; b, 0.0010% to 0.0030% of the raw materials; 0.02% to 0.06% of Al; p < = 0.005%; s < = 0.002%; o < = 0.0025%; n < = 0.0040%; h is less than or equal to 0.00015%, and the balance is Fe and inevitable impurity elements. According to the steel plate, through reasonable chemical component design and full utilization of the mutual matching effect of various elements, on one hand, the strength of the steel plate is enhanced, and on the other hand, the elements achieve the grain refining effect under the appropriate technology, so that the steel plate has high plastic deformation and ultrahigh yield strength, and the yield strength of the steel plate can reach 1100 MPa.