Abstract: In order to meet the demand of automotive industry for high-strength and high processability materials， a cold-rolled low-alloy high-strength steel HC420LA with excellent comprehensive performance was developed. Then， by using the C-Mn-Nb-Ti composite microalloy composition design method and combining with the optimized hot rolling and annealing process system， the parameters of heating temperature， reduction rate of cold rolling， annealing temperature and annealing speed in the whole process were systematically studied by thermal simulation technology to ensure the stability of product quality.The results show that the developed cold-rolled low-alloy high-strength steel has excellent mechanical properties， with a yield strength of 433 to 492 MPa， a tensile strength of 510 to 581 MPa， and an elongation after fracture of 18.5% to 25.5%， which fully meets the processing requirements of automotive OEMs. The finished product is a ferrite single-phase structure with good structure deformation ability， showing excellent cold bending and hole expansion performance. At the same time， the banded structure in the finished product structure is mainly due to insufficient recrystallization. By increasing the annealing temperature and reducing the annealing speed， the anisotropy is effectively reduced， and the material performance is further optimized. Thus， this study provides a reference for the formulation of process parameters in the industrial production of similar products and is beneficial to promote the development and application of high-strength steel.