The invention discloses a Q345-serie super-thick steel plate having a low cost and guaranteeing performances and flaw detection, and a production technology thereof. The Q345-serie super-thick steel plate has the thickness of 100 to 200mm. The Q345-serie super-thick steel plate comprises 0.08 to 0.17wt% of C, 0.15 to 0.40wt% of Si, 1.00 to 1.30wt% of Mn, less than or equal to 0.020wt% of P, less than or equal to 0.020wt% of S, less than or equal to 2.0wt% of microalloying elements comprising V, Nb, Ti, Cr and Ni, 0.020 to 0.050wt% of Als and the balance Fe and residual elements. The production technology comprises the following steps of KR molten iron pretreatment, converter
smelting, LF refining, vacuum refining,
continuous casting,
casting blank heating, rolling,
slow cooling and heat treatment. Through a reasonable
chemical composition design and the LF and VD refining processes, steel cleanliness is guaranteed. Through
superheating, rolling and normalizing treatment, the Q345-serie super-thick steel plate having the thickness of 100 to 200mm and guaranteeing performances and flaw detection is prepared by the
continuous casting technology. The Q345-serie super-thick steel plate has yield strength of 310 to 400MPa, tensile strength of 490 to 580MPa, percentage elongation of 22 to 27% and V-notch
impact energy of 80 to 200J.