Abstract: The total potential of purifying SO₂ of main tree species was studied by using the combination of field measurement and fumigation experiment in this paper.The integrated value of purifying SO₂ including total bimass,absorption intensity of SO₂,and absorption transformation periods of sulfur by trees was 4.39?10⁶ kg,which was accouted for 3.66% of total sulfur released per year in Shenyang.It indicated that the maximum daily potential of purifying SO₂ of trees might be 12.19kg穔m^-2.Supposed that the average annual absorption capacity for sulfur of tress in Shenyang was 0.70 kg per tree and the average annual absorption capacity for sulfur of broad leaved trees was 1.35kg穞ree^-1,88.88 million broad leaved trees would be required to purify the annual released SO₂ thoroughly.This number was equivalent to 12.9 times of existing trees.On the conditions of strengthening environmental protection and decreasing 20% of annual released sulfur,if the broad leaved trees was double of the present number,SO₂ content in air might be below 0.06 mg穖^-3 and Shenyang would become a standardizing city with clear air.

Key words: Shenyang area, Main tree, Potential of purifying SO₂, Quota of planting tree