Abstract: Compound fertilizer can improve the fertilizer use efficiency and tree nutrition status to ensure balanced fertilization. Taking 7 year-old chestnut trees as test material, with (NH₂)₂CO and KH₂PO₄ being mixed at the different ratios, the effects of different compound fertilizers on the photosynthesis characteristics as well as the growth and fruiting of chestnut were studied quantitatively by trunk injection method. Results showed that compound fertilizer of (NH₂)₂CO and KH₂PO₄ induced positive synergistic effects to enhance photosynthetic capacity, yield and quality of chestnut obviously. The content of chlorophyll was decreased by (NH₂)₂CO and increased by KH₂PO₄, but increased obviously by the compound fertilizer. The contents of N, P, K of leaf and branch rose under the four compounded fertilization treatments, among which 0.3%(NH₂)₂CO+0.3%KH₂ PO₄ was the best. All fertilizer treatments could advance the photosynthetic parameters, while the compound fertilizer performed better. 0.3%(NH₂)₂CO+0.3%KH₂PO₄ treatment significantly increased the photosynthetic rate, the maximum net photosynthesis, apparent quantum yield, carboxylation efficiency, instantaneous water use efficiency and nitrogen use efficiency. Compound fertilizer could promote the growth of branch in diameter and length synchronously, and increase the number of mixed buds, while (NH₂)₂CO only promoted the growth of branch in length, and did little in the number of mixed buds. The compound fertilizer did better in advancing nuts yield and quality than single fertilization of N or P. The nuts yield, mass and total sugar were increased by 68.2%, 25.5% and 14.9% respectively under 0.3%(NH₂)₂CO+0.3%KH₂PO₄ treatment compared with the control.