Abstract: In order to study the seismic behavior of corroded steel frames under offshore atmospheric environment, accelerated corrosion tests on 42 tensile coupons and 4 plane steel frames were implemented by the technique of artificial climate accelerated corrosion. Tensile tests were then performed to obtain the functional relationships between mechanical properties (including yield strength, ultimate strength, elongation and elastic modulus) and weight loss rate for Q235B steel subjected to corrosion. 4 plane steel frames were tested under lateral low cyclic loading. The effects of corrosion degrees on the failure mechanism, hysteretic behavior, skeleton curves, stiffness degradation, ductility and energy dissipation capacity of the specimens were analyzed. The test results show that all specimens exhibit ductile failure with a hybrid yield dissipation mechanism. While the corrosion degree increases, the load bearing capacity and energy dissipation capacity decrease significantly, the strength and stiffness degrade obviously, and the ductility is reduced. Based on the experimental study, nonlinear finite element analyses were conducted on the test plane steel frames using ABAQUS. The influence of axial compression ratio on the mechanical properties of specimens were analyzed. The results indicate that with the increase of the axial compression ratio, the bearing capacity and ductility decrease monotonically.