The invention relates to a production method of an easily formable high-strength medium-thick steel plate. The method comprises the following process steps: converter steelmaking, ladle furnace refining, vacuum treatment vacuum treatment, continuous casting, heating, rolling, pre-straightening, on-line quenching and tempering heat treatment. The mass percent composition of the steel is as follows: C = 0.06-0.08, Si = 0.15-0.30, Mn = 1.40-1.60, P <= 0.015, S <= 0.005, Nb + V + Ti <= 0.16, Cr + Mo <= 0.4, Alt = >0.020, and Pcm <= 0.21. The Q620E steel plate with a thickness of 200mm produced by the method is good in cold bending, and the cold bending property of the steel plate real object meets the easily forming requirement of users; the yield ratio of the steel plate is smaller than 0.92, and the uniform elongation rate is larger than 8%, which meets the use requirements of relevant designs; the product of strength and elongation is increased by more than 35%, the capacity of resisting dynamic loading of the high strength steel plate is increased, and the equipment safety is improved; through hot charging and on-line quenching of the continuous casting, the production cost is reduced; and with the component design in which Pcm is smaller than 0.21%, the welding properties welding property of the high strength steel plate is improved.