Abstract: Pot experiments were used to identify the effects of lithium levels on growth, chlorophyll content and chlorophyll fluorescence parameters of Apocynum venetum. When A. venetum was exposed to lithium either by foliage spray or root application, variation lithium level had an obvious influence on plant growth and appearance. The concentrations of lithium used were 0, 5, 10 and 20 mg/kg, and growth rate and fluorescence parameters (including F_v/F_m, F_v/F_o, Ψ_o, φ_Eo, PI_ABS, photosynthetic pigments contents, S_m) of A. venetum were measured. All parameters significantly increased in proportion to lithium application rate at lower lithium levels, but growth and fluorescence parameters were generally lower at 20 mg/kg than at 10 mg/kg, at higher levels, indicating toxicity at the higher rate. Similarly, stem diameter, plant height, and the number of leaves on the main and branch of A. venetum were also responsive to lower levels of applied lithium. The margin between beneficial and toxic lithium concentrations was very small. Therefore, the lithium concentration in plant growth media or foliar application should be strictly controlled when cultivating A. venetum.