The invention discloses a high-strength ultra-thick steel plate. The high-strength ultra-thick steel plate is prepared from the following components in percentage by mass: 0.10 to 0.16 percent of C, 0.35 to 0.45 percent of Si, 1.35 to 1.55 percent of Mn, 0.15 to 0.50 percent of Ni, 0.001 to 0.25 percent of Cr, at most 0.008 percent of P, at most 0.005 percent of S, 0.015 to 0.04 percent of Al, 0.06 to 0.08 percent of V and 0.0090 to 0.015 percent of N, wherein the content of N is greater than or equal to 0.5*0.529*content of Al<+>0.2*0.275*content of V and is less than or equal to 0.8*(0.529*content of Al<+>0.275*content of V), and the balance is Fe. The thickness of the high-strength ultra-thick steel plate is 200mm to 400mm; the high-strength ultra-thick steel plate is subjected to normalizing treatment, and the normalizing technology is that air cooling or water cooling is carried out after even temperature is kept by heating at the temperature of 890 DEG C to 930 DEG C. A one-quarter position and the center position of the cross section of the high-strength ultra-thick steel plate are provided with small ferritic structures and a small amount of pearlitic structures, and the grain size is greater than 8-grade standard of ASTM (American Society for Testing Material).