This study focused on the effects of magnesium (Mg2+) on growth, photosynthetic characteristics and chlorophyll fluorescence parameters of Tung tree leaves under sandy culture conditions. The results showed that the optimal concentrations of Mg2+ for Tung tree growth and photosynthesis were 2-4 mmol • L-1. Under low Mg concentration (Mg2+4 mmol • L-1), the growth of Tung tree was also inhibited. The chlorophyll content, RuBP carboxylase activity, Pn, Gs, Fv/Fm, Fv/Fo andqP were reduced (P