Abstract: For the system to understand the low temperature environment the influence of exogenous superoxide dismutase（SOD） of petunias physiological characteristic, help garden plant petunias safe wintering, artificial environment to set low temperature stress petunias cultivation experiment was carried out for the object, from the growth index, peroxidase（POD） enzyme activity, nitrogen phosphorus and potassium（NPK）elements content three aspects study the effect of exogenous SOD of petunias physiological characteristics; The results showed that exogenous SOD mimics could improve stem and leaf length, root length, lateral root number, POD enzyme activity and nitrogen, phosphorus and potassium absorption capacity of petunias under low temperature stress, and 8.5 mg·L^-1 of three MSOD concentrations had the best effect. In conclusion, petunia can optimize physiological indexes and promote its growth by applying appropriate amount of exogenous SOD in low temperature environment.