Abstract: This paper show that:Both chlorine content and memberane permeability of leaves of trees increased with seasons.Chlorophyll contents of trees polluted by chlorine decreased,remarkably.Absorptive capacity of trees is not equal to hardiness completely.Though capacity of chlorine absorptive of elm was more intensive than other trees,hardiness of elm against chlorine was in middle levels.Either capacity of chlorine absorption or hardiness of poplar was in middle levels,which of boxelder in lower level.Willow possessed intensive capacity of chlorine absorption,and could withstand chlorine harm.

Key words: Chlorine, Trees, Chlorine content, Hardiness