The invention discloses a low-yield-ratio and high-strength steel plate and a production method thereof. The steel plate comprises chemical components including, by mass percent, 0.05%-0.08% of C, 0.15%-0.35% of Si, 1.40%-1.55% of Mn, smaller than or equal to 0.015% of P, smaller than or equal to 0.010% of S, 0.020%-0.035% of Al, 0.10%-0.15% of Cr, 0.12%-0.20% of Mo, 0.020%-0.030% of V, 0.020%-0.030% of Nb and the balance Fe and inevitable impurities. The production method comprises the procedures of billet heating, controlled rolling, cooling after rolling and straightening. The low carbon and low alloy component design is adopted, the steel plate is controlled to be subjected to relaxation for a certain time after being rolled and then enters water to be cooled, the obtained steel platecompletely meets the standard and safety requirement, and the steel plate is suitable for manufacturing of hydroelectric structure piece and chemical product storage and transportation equipment.