Abstract: The effects of simulated SO₂ treatment on the photosynthetic apparatuswere investigated in twelve wetland woody plants. After leaf sections were immersed in 0, 10, 20, 30, 40, 50, and 100 mmol/L NaHSO₃ for 20 hours, maximumquantum yield and maximum electron transport rate of all twelve woody plants reduced to different degrees with increasing SO₂ concentration. Such a finding suggestedthat photosystem Ⅱ reaction centers were damaged by SO₂ stress, electron transport was prohibited and photosynthetic efficiency decreased. Dendrograms indicated that the resistant species were Quercus palustris, Sapium sebiferum， andFraxinus griffithii. The sensitive species was Taxodium distichum.