In order to investigate the effects of Cinnamomum japonicum leaf litter addition on the physiological properties of Impatiens balsamina,a pot experiment has been conducted.Four litter addition treatment levels (0,20,40,80 g·pot^-1) were applied.The results showed that:(1)Litter additions significantly increased H₂O₂ concentration in leaf of I.balsamina in pre-squaring stage.(2)The activities of superoxide dismutase(SOD),peroxidase(POD) and catalase(CAT) were inhibited significantly during pre-squaring,squaring and full bloom stages.(3)Ascorbic acid(ASA) concentration was significantly increased in pre-squaring stage,but decreased significantly in squaring and full bloom stages.(4)The basal diameter growth and aboveground biomass of I.balsamina were depressed by the litter additions significantly.(5)Coumarin,eudesmol,cinnamic aldehyde,trans-caryophyllenethe and terpineol may the main allelochemicals in C.japonicum leaf litter.The study suggests that the non-enzymatic ROS scavenging system may more important than the enzymatic system for I.balsamina.Ascorbic acid may play an important role in the resistance of oxidative stress in pre-squaring stage of I.balsamina.The oxidative stress derived from litter additions may exceed the scavenging capacities of the two systems,and as a result,the basal diameter growth and aboveground biomass accumulation were depressed by the injury of membrane system of I.balsamina.