Abstract: A cold-rolled dual-phase steel was pre-deformed in different degrees, and then was baked in different processes. The effects of pre-deformation degree, baking time and aging at room temperature, on bake hardening behavior were investigated, then their effect mechanism was also analyzed. Results show that the BH value of the steel increases continuously with the increment of pre-deformation degree and prolongation of baking time; the bake hardening behavior is too stable to loose efficacy. The bake hardening mechanism of the dual-phase steel was described as a coefficient result of Cottrell atomosphere formation, tempering of martensite, decomposition of residual austenite and precipitation of carbide.