To reveal the effects of light intensity，nitrogen application and their interaction on the growth and photosynthetic physiology of Erythrophleum fordii seedlings，a two-factor pot experiment with four nitrogen levels(0.0，2.0，4.0，6.0 g/plant)and four light levels(100%，51.67%，25.50%，9.30% natural sunlight，marked as NS)was conducted to study the growth and photosynthetic physiological characteristics of Erythrophleum fordii seedlings under the light-nitrogen interactions，taking the first-year Erythrophleum fordii seedlings as materials. The results showed that:(1)The main effects of light and nitrogen，as well as their interaction，had an extremely significant impact on the plant height increment，chlorophyll and carotenoid content，net photosynthetic rate，RuBP carboxylase，PEP carboxylase，Na+K+-ATPase，Ca2+Mg2+-ATPase and total ATPase(P<0.01)，and there was a significant or extremely significant interaction effect between different light and nitrogen levels. Applying nitrogen fertilizer effectively alleviated the inhibition of shading on the photosynthesis of Erythrophleum fordii seedlings. (2)At the same nitrogen level，the increment of height，ground diameter，net photosynthetic rate，stomatal conductance，transpiration rate，PEP carboxylase，Na+K+-ATPase，Ca2+Mg2+-ATPase，and total ATPase of Erythrophleum fordii seedlings showed a tendency of increasing and then decreasing with the decrease of light intensity，except Na+K+-ATPase，Ca2+Mg2+-ATPase，all of them were the highest at 51.67%NS. In contrast，RuBP carboxylase in the same period of leaves was decreased and then increased with decreasing light intensity，and was generally the highest at maximum natural sunlighty. (3)Compared with L0N0(100%NS+0.0 g/plant) treatment，shading and nitrogen application significantly increased the photosynthetic pigment content of Erythrophleum fordii seedling leaves，but excessively high nitrogen levels also inhibited the synthesis of photosynthetic pigments. (4)Based on comprehensive analysis，it was concluded that the treatment effect of the L1N2 treatment(51.67%NS+N 4.0 g/plant)on Erythrophleum fordii seedlings was the best. The study showed that the appropriate light intensity and nitrogen level were conducive to improving the absorption，conversion and utilization of light energy by the leaves of Erythrophleum fordii seedlings，improving their photosynthetic performance，promoting the synthesis of carbon assimilates，and thus enhancing the quality of seedlings.