Abstract: The mechanical properties of steel will deteriorate after corrosion. The existing studies mainly focuses on the static tensile properties of low carbon steel. In order to study the mechanical properties of Q345B low-alloy steel after corrosion, tested are 22 groups of Q345B steel subjected to artificial accelerated corrosion, to monotonic tensile and cyclic loading. The effects of corrosion on monotonic tensile and hysteretic properties of materials were analyzed. Based on the Chaboche plastic constitutive model, the isotropic hardening and kinematic hardening parameters were calibrated and verified according to the test data. The results show that the tensile stress-strain curve of steel is obviously affected by corrosion, and all mechanical indexes show linear or nonlinear degradation with the increase of corrosion. The coupling effect of cyclic cumulative damage and corrosion will further aggravate the deterioration of steel deformation capacity, and the energy dissipation capacity and cyclic strengthening of steel will also be affected by corrosion. The hardening parameters calibrated can effectively describe the hysteretic performance of corroded Q345B steel and provide a support for the subsequent analysis of residual seismic capacity of steel members and structures in service.