In this thesis, based on the low-carbon bainitic steel HQ785, isothermal transformation tests are carried out on the Gleeble-3500 thermo-mechanical simulator under uniaxial external tensile stress state. The fully immersed accelerated corrosion tests for the specimens, with different microstructure after phase transformation are carried out. The corrosion behavior of experimental steel is evaluated, combing with OM, SEM, weight loss method and electrochemical method. The results show that the shape of phase transformation microstructrue varies from granular to lath with the increase of external tensile stress. The corrosion resistance of which is better than that of granular bainite without stress. The sample with rusty layer after full immersion seawater corrosion shows good protectiveness.