The invention discloses a manufacturing method of a thick-specification high-surface-quality hot-rolling and straightening steel sheet. The chemical components of the steel sheet comprise, in percentage by weight, 0.05-0.25% of C, 0.005-0.20% of Si, 0.10-2.0% of Mn, less than or equal to 0.025% of P, less than or equal to 0.025% of S, 0.020-0.070% of Als, 0.005-0.10% of Nb, 0.001-0.20% of V, 0.01-0.15% of Ti, 0.0001-0.005% of B and the balance Fe and impurities. According to the impurity requirement, Ni is less than or equal to 0.30%, Cr is less than or equal to 0.20%, Mo is less than or equal to 0.08%, Cu is less than or equal to 0.35%, Sn is less than or equal to 0.03%, and Pb is less than or equal to 0.02%. The hot-rolling and straightening steel sheet is prepared through blast-furnace molten iron, pre-desulfuration, converter smelting, LF+RH refining, sheet blank continuous casting, casting blank slowly cooling, sheet blank heating, hot continuous rolling, ultra fast cooling + laminar cooling, coiling, uncoiling, seven-roller coarse straightening + eleven-roller fine straightening and transversely cutting. The hot-rolling and straightening steel sheet produced through the invention with the thickness specification being 14-25 mm and the strength level being smaller than or equal to 400 MPa is excellent in mechanical performance and good in surface quality and has obvious competitive advantages in industries such as ships, engineering machinery and bridges.