Abstract: High-strength steel structures are frequently exposed to corrosion during service, and their subsequent exposure to fire may further increase the risk of severe damage or structural failure. To investigate the post-fire mechanical behavior of corroded Q690 high-strength steel, both uncorroded fire-exposed specimens and corroded fire-exposed specimens were tested in this study. The experimental program included electrochemical corrosion, elevated-temperature exposure, air and water cooling, followed by tensile testing. Based on the test results, a mathematical model incorporating the effects of corrosion level, exposure temperature, and cooling regime was developed to predict the residual mechanical properties of corroded Q690 steel after fire exposure. In addition, a randomly distributed corrosion finite element model was established using the Monte Carlo method, and numerical analyses were conducted for specimens with different corrosion ratios. The test results show that the corrosion is the main factor affecting the mechanical properties of high strength steel when the temperature is lower than 500 ℃; When the temperature is higher than 500 ℃ and lower than 700 ℃, the increase of temperature significantly accelerates the degradation of mechanical properties of corroded Q690 high-strength steel; When the temperature is further increased to 700 ℃, different cooling modes have obvious effects on the mechanical properties of high-strength steel under the same corrosion rate and temperature.