Tobacco (Nicotiana tabacum L.) seedlings were used to evaluate the effects of exogenous Cd²⁺ on hormone levels, photosynthetic and fluorescent characteristics. Seedlings with six leaves and same height were hydroponically cultivated in Hoagland's nutrient solution for 15 d. The seedlings were aerated 3 h per day and the nutrient solution was renewed every 5 d. Afterwards, Cd (NO₃)₂ was added to the nutrient solution at 0, 5, 25 and 50 mg/L, respectively (calculated as pure Cd²⁺). After Cd²⁺ treatment for 3 d, the Cd²⁺ contents in leaves were determined with inductively coupled plasma atomic emission spectrometer. The levels of endogenous phytohormones including indoleacetic acid (IAA), gibberellic acid (GA₃), abscisic acid (ABA) and zeatin (Z), were assayed with enzyme-linked immunosorbent assay (ELISA). The activities of indoleacetic acid oxidase (IAAO), photosynthetic performance and chlorophyll fluorescent characteristics were measured. Our results showed that the contents of Cd²⁺ in leaves significantly increased with the increase of exogenous Cd²⁺ concentration, the activities of IAAO decreased at Cd²⁺ 5 mg/L, but increased at higher concentrations of exogenous Cd²⁺. At Cd²⁺ 50 mg/L, the activity of IAAO increased by 101.71% comparison with the control. Both of the contents of IAA and GA₃ increased at Cd²⁺ 5 mg/L, but decreased with the increase of exogenous Cd²⁺ concentration. At 50 mg/L Cd²⁺, the contents of IAA decreased by 34.10%, the contents of GA₃ decreased by 39.69%, while the contents of ABA gradually increased with Cd²⁺ concentration increase. At 50 mg/L Cd²⁺, the contents of ABA increased by 61.84% comparison with the control. However, the contents of Z sharply decreased with the increase of Cd²⁺ concentration, and the contents of Z decreased by 75.35% at 50 mg/L Cd²⁺. Moreover, the contents of chlorophyll a and b and carotenoid decreased significantly with the increase of exogenous Cd²⁺ contents. At 50 mg/L Cd²⁺, chlorophyll a and b and carotenoid declined by 34.80%, 55.80% and 73.77%, respectively, comparison with the control. All photosynthetic parameters such as net photosynthesis rate (Pn), stomatal conductance (Gs), intercellular CO₂ concentration (Ci), transpiration ratio (Tr) decreased with the increase of Cd²⁺ concentration in the nutrient solution. The fluorescent parameters including PSⅡ potential activity (Fv/Fo), maximal efficiency of PSⅡ photochemistry (Fv/Fm), efficiency of PSⅡ photochemistry (ФPSⅡ), photochemical quenching coefficient (qP) decreased with the increase of exogenous Cd²⁺. Besides, variable chlorophyll fluorescence (Fv) and maximum chlorophyll fluorescence (Fm) decreased sharply. Pn, Gs, Ci and Tr decreased by 47.59%, 66.67%, 28.94% and 60.82% respectively, at 50mg/L Cd²⁺. It suggested that Cd²⁺ stress disturbed the balance of phytohormone levels in tobacco leaves, and caused the decrease of photosynthetic capacity of tobacco leaves.