The invention discloses a Q690-grade high-strength steel plate and a manufacturing method thereof, and relates to the field of steel smelting. The Q690-grade high-strength steel plate comprises the following chemical components in percentage by mass: 0.15-0.19% of C, 0.20-0.50% of Si, 1.00-1.30% of Mn, not more than 0.020% of P, not more than 0.005% of S, 0.02-0.04% of Nb, 0.10-0.40% of Cr, 0.20-0.40% of Mo, 0.010-0.030% of Ti, 0.030-0.06% of V, 0.0010-0.0030% of B, 0.020-0.060% of Alt, not more than 0.0050% of N, not more than 0.0002% of H, and the balance of Fe and inevitable impurities. Thesteel plate guarantees higher strength and hardness, in particular higher core hardness under the condition of tempering temperature not lower than 620 DEG C.