Ground cover plants are one of the essential landscape plant species among the current urban greening,and understanding the physiological mechanism of these plants resistance to sulfur dioxide (SO₂) can help us choose the suitable species.In this study,three ground cover plant species (Petasites japonica,Stachys lanata and Trigonotis omeiensis) growing under the greenhouse condition were selected and screened for tolerance to acute SO₂ injury.Four SO₂ treatments including 0,5.71,11.43,and 17.14 mg·m^-3 were used in this study,and release of SO₂ were achieved using the artificial simulated fumigation method.Differential response to SO₂ injury among these three species was manifested through the phenotypic injuries and the various physiological indexes.Our results showed that:(1)the phenotypic injury of three species is ordered in sequence from severe to light as S.lanata>T.omeiensis>P.japonica.The content of chlorophyll and the value of leaf pH decreased gradually with the increase of SO₂ concentration,while the levels of MDA content,the electrolyte leakage rate,and the contents of soluble sugar and the proline rose in the varying degree among the three species.Furthermore,the activities of superoxide dismutase(SOD),peroxidase(POD),catalase(CAT) were activated dramatically.(2)Through the subordination function and principal component analysis,we concluded that the resistance to SO₂ among these three species is ordered in sequence from high to low as P.japonica>T.omeiensis>S.lanata.(3)The purification ability to SO₂ is ranked in order from high to low as P.japonica>S.lanata>T.omeiensis by analogizing sulfur accumulation within leaf under SO₂ stress.The results shows that P.japonica has the strongest capacity of resistance and purification of SO₂ and it can also has no obvious phenotypic injury through its own stress protection system to improve resistance to SO₂.This conclusion can guide us in respect of large-scale use of P.japonica in heavily SO₂-polluted urban areas.