This　paper　studies　Q235　steel　corrosion　behavior　and　mechanism　in　the　typical　marine　environment,　a　corrosion　model　of　Q235　steel　with　a　defective　passivation　film　in　a　marine　atmospheric　environment　is　developed　based　on　the　electrochemical　corrosion　module　in　the　COMSOL　software,　and　the　whole　corrosion　process　is　simulated　by　means　of　finite　element　analysis.　The　results　show　that　the　corrosion　of　Q235　steel　in　the　marine　atmospheric　environment　starts　at　the　passive　film　defect,　and　over　time,　it　gradually　develops　from　pitting　corrosion　to　intergranular　corrosion,　and　then　gradually　develops　from　intergranular　corrosion　to　comprehensive　corrosion.　The　whole　corrosion　process　is　from　point　to　surface.　In　addition,　a　rapid　assessment　model　of　the　corrosion　life　of　Q235　steel　was　established　by　cyclic　salt　spray　accelerated　corrosion　test.　It　is　verified　that　the　kinetics　of　the　corrosion　weight　loss　of　the　Q235　steel　is　in　accordance　with　the　power　function　law,　and　also　observed　that　Q235　steel　surface　passivation　film　as　well　as　passivation　film　rupture　after　the　generation　of　dense　alpha-FeOOH　rust　layer　all　play　a　role　in　resisting　corrosion.