Abstract: Through comparative study on toxic effect of Cr ⁶⁺ and Cr ³⁺ on some biochemical and physiological characters of leaves and roots of A.philoxeroides,it has been found that A.philoxeroides was injured by the pollution of Cr ⁶⁺ and Cr ³⁺.When polluted,the five major biochemical and physiological indexes of the plant,including the content of chlorophyll,SOD,POD, CAT activity and the content of soluble protein all changed,rising first and then falling,or keeping on rising or keeping on falling.The toxic effect of Cr ⁶⁺ was much stronger than that of Cr ³⁺ and the damage was greater to roots than to leaves.