Abstract: 【Objective】 In order to clarify the effect of nitrogen reduction on photosynthetic efficiency of pepper, the relationship between nitrogen content and photosynthetic efficiency under different nitrogen reduction levels was analyzed. 【Method】 Four nitrogen application levels were set in pots,Seedling period: N₁(47.52 kg/hm²)、N_0.8(38.03 kg/hm²)、N_0.6(28.50 kg/hm²)、N₀(0 kg/hm²);Fruit setting period: N₁(79.20 kg/hm²)、N_0.8(63.36 kg/hm²)、N_0.6(47.52 kg/hm²)、N₀(0 kg/hm²). 【Results】 Under the N_0.6 treatment at the seedling stage, the growth index and photosynthetic parameters of pigment pepper were the largest, and the net photosynthetic rate increased by 8.6%, 9.8% and 13.5% compared with the N₁, N_0.8 and N₀ treatments, respectively.The maximum carboxylation rate (V_cmax) increased by 7.6%, 8.3%, and 9.3%.; The maximum electron transfer rate (J_max) increased by 17.1%, 18.4%, and 21.8%.Under the N_0.8 treatment of fruit setting, the growth index and photosynthetic parameters of pigmented pepper were the largest, and the net photosynthetic rate was increased by 10.0%, 10.2% and 15.4% compared with N₁, N_0.6 and N₀ treatments, respectively.V_cmax increased by 4.9%, 6.3%, and 13.4%; J_max increased by 0.6%, 15.8%, and 21.9%, respectively.Under the N_0.8 treatment at the seedling stage, the production of pigmented peppers increased by 1.8%, 2.5% and 2.8% compared with N₁, N_0.6 and N₀, respectively.Under the N_0.8 treatment of fruit setting, the production of pigmented peppers increased by 6.3%, 11.6% and 17.6% respectively compared with N₁, N_0.6 and N₀.Analysis over both periods showed that as nitrogen application decreased, peppers increased in specific leaf weight (LMA) and photosynthetic nitrogen use efficiency (PNUE) and decreased specific leaf nitrogen (Narea); Nitrogen application levels also have an effect on nitrogen distribution in photosynthetic organs, and the proportion of nitrogen in the photosynthetic system gradually increases with the decrease of nitrogen application, and the proportion of nitrogen in non-photosynthetic systems decreases with the decrease of nitrogen application.The proportion of nitrogen in the photosynthetic components of pepper leaves was significantly positively correlated with PNUE, and the proportion of non-photosynthetic components was significantly negatively correlated with PNUE. 【Conclusion】 Within the scope of this test, the most suitable nitrogen application rate for the growth of pigmented pepper seedlings was N_0.6 treatment, while the most suitable nitrogen application amount for reproductive growth was N_0.8 treatment, and the fruit setting stage was N_0.8 treatment, that is, the N_0.8 treatment in both stages was more conducive to the formation of pigment pepper yield.