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Cyclocarya paliurus has been traditionally used as a functional food in China. A hydroponic experiment was conducted to determine the effects of N and P additions on photosynthesis and chlorophyll fluorescence (ChlF) of C. paliurus seedlings. N and P additions significantly altered photosynthesis and ChlF in the seedlings, but responses of these parameters to the N and P concentrations varied at different developmental stages. The greatest net photosynthetic rate (PN) and actual photochemical efficiency of PSII (ФPSII) occurred in the treatment of 150.0 mg(N) L-1 and 25.0 mg(P) L-1 addition, whereas the highest maximum quantum yield of PSII (Fv/Fm) and water-use efficiency (WUE) were recorded with 150.0 mg(N) L-1 and 15.0 mg(P) L-1 on the 60th day after treatment. Significantly positive correlations of PN with leaf relative chlorophyll content, transpiration rate, WUE, Fv/Fm, and ΦPSII, as well as the ФPSII with the Fv/Fm, were found. Our results indicated that an optimal addition of N and P nutrients depends on their coupling effects on the photosynthetic capacity and PSII photochemistry.