The invention relates fine crystallization hot-rolled diphase steel, comprising 0.06- 0.10wt% C, 0.4-1.2wt% Mn, 0.015-0.45wt% Si, 0.015-0.04% Nb, 0.005-0.03wt% Ti, less 0.003wt% S, 0.034wt% Al, 0.014wt% P, and Fe. The method comprises the following steps: heating, heat preservation, rough rolling at the temperature between 1050-1150Deg.C, fine rolling at the beginning temperature between 930-960Deg.C and at the ending temperature between 790-850Deg.C, cooling, and batching; controlling the press down content between 19% and 33%. The product possesses the good mechanics properties of 500- 610MPa strength for extension, 20-30% elongation and less 0.7 yield ratios. The method is low cost and suits for industrial production. |