Production method of super-thick steel plate with even performance in thickness direction

The invention provides a production method of a super-thick steel plate with even performance in the thickness direction. The plate is rolled by a pair of female blanks after vacuum welding. Continuous castings are adopted for the female blanks, the welding surfaces of the female blanks are lower surfaces of the continuous castings, and the roughness is larger than 6.3mum; and vacuum composite blanks are heated and rolled, high-temperature large screw-down rolling is adopted for the first three passes, for composite blanks with widths smaller than 1650mm, all the screw-down rates for the first three passes are >=10%, for composite blanks with widths larger than 1650mm, the screw-down rate for the first pass is >=5%, and the screw-down rates for the second and third passes are >=10%. According to the plate, the source and the size of the female blanks are wide, the quality is stable, defects such as segregation and loosening in the middle of finished steel plates are overcome, the rolling yield is high, the performance of the steel plate is even in the thickness direction, and the Z-directional performance can reach above 35%.