Objective To study the influence of atmospheric environment on steel transmission tower. Methods The corrosion behavior of carbon steel in different concentration of SO₂ and different relative humidity was investigated using accelerated corrosion test. Results Severe corrosion occurred for carbon steel in SO₂ environment with high relative humidity. Oxygen corrosion was the main corrosion type. The corrosion rate of carbon steel was greatly reduced in a low relative humidity environment. As the SO₂ concentration increased, the corrosion rate did not significantly increase. Conclusion Reducing relative humidity could effectively prevent or slow down the corrosion of carbon steel in SO₂ environment.