The invention relates to a production method of an ultrahigh-strength anti-cracking thick steel plate. The steel comprises the following chemical components in percentage by weight: at most 0.10% of C,0.10%-0.50% of Si, 1.40%-1.80% of Mn, at most 0.015% of P, at most 0.005% of S, 0.02%-0.05% of Nb, 0.008%-0.02% of Ti, 0.015%-0.05% of Al, 0.2%0-0.50% of Ni, at most 0.35% of Cu, at most 0.25% of Gr, at most 0.25% of Mo, and the balance of Fe and inevitable impurities. The production method comprises the following key steps: smelting, continuous casting, heating, rolling and cooling. By adopting the low-carbon high-manganese Nb-Ti-Ni multielement microalloying component design system in combination with LF+VD (ladle furnace+vacuum degasser) compound refining and ultra-fast cooling techniques, the ultra-thick steel plate with the yield strength of 400 MPa above and the maximum thickness of 80mm can be produced. The -40-DEG C impact toughness of the steel plate core can reach 250J above, the nil ductility transition temperature is -80 DEG C below, and the high-strength steel plate has higher toughness, weldability and cracking resistance.