The invention discloses a super-thick steel plate for a turbine partition ring and a production method of the super-thick steel plate. The steel plate comprises the following chemical components of, in percentage by mass, 0.13%-0.17% of C, 0.15%-0.35% of Si, 0.55%-0.80% of Mn, less than or equal to 0.015% of P, less than or equal to 0.015% of S, 0.80%-0.95% of Mo, 0.15%-0.20% of Ni, 0.80%-1.1% ofCr, 0.15%-0.20% of V, 0.020%-0.050% of Alt, and the balance Fe and inevitable impurities; and the production method comprises the steps of steelmaking, continuous casting, heating, rolling and heat treatment. According to the super-thick steel plate and the production method of the super-thick steel plate, the components are accurately controlled, the micro-alloy elements Ni and Cr are added in acomposite mode, a controlled rolling and controlled cooling production process is adopted, the inner quality of the produced steel plate is excellent and the performance is stable, the use requirementof the steel plate for the partition ring of the steam turbine is completely met, and the requirement of the structural steel market is better met.