High-strength steel plate with improved low-temperature impact toughness and manufacturing method thereof

The invention discloses a high-strength steel plate with improved low-temperature impact toughness. The high-strength steel plate is manufactured from the chemical ingredients comprising, by mass percent, 0.07% to 0.19% of C, 0.15% to 0.45% of Si, 1.15% to 1.65% of Mn, not larger than 0.025% of P, not larger than 0.008% of S, not larger than 0.04% of Nb, not larger than 0.20% of V, not larger than 0.015% of Ti, 0.005% to 0.030% of Alt, not larger than 0.020% of N, 0.002% to 0.003% of O, 0.005% to 0.010% of Y, 0.015% to 0.025% of Ce and the balance Fe, rare earth and inevitable impurities. The rare earth is yttrium-based rare earth, and a composite inclusion component in steel comprises, by mass percent, 25.72% to 69.15% of Y and 3.09% to 17.52% of Ce. The matrix structure of the steel plate is a fine ferritic and pearlitic structure. The yttrium-based rare earth is used for achieving the functions of purifying, denaturating, microalloying and oxide metallurgy in the steel, and the low-temperature impact tough