The invention discloses a high-strength steel with bimodal scale ferrite structure and a low cost preparation method thereof. Ordinary low carbon steel is adopted as a raw material plate, cold deformation and two-phase region quenching are carried out to obtain a bimodal scale structure with fine quasipolygonal ferrite grains distributed around coarse polygonal ferrite grains, the fine quasipolygonal ferrite grains plays a role of strengthening phase, and the coarse polygonal ferrite grains guarantee the steel plasticity. The high-strength steel prepared by the preparation method provided by the invention has excellent comprehensive mechanical properties, yield strength of greater than or equal to 650MPa, tensile strength of greater than or equal to 800MPa, uniform elongation of greater than or equal to 10.0%, a work hardening index of greater than or equal to 0.20, and a yield ratio of less than 0.90. At the same time, the process is simple and the production cost is low.