Abstract: A field experiment was carried out to investigate the effect of different nitrogen on growth of Camptotheca acuminata seedlings, photosynthesis, leaf nutrient elements and camptothecin content by determine the variation of photosynthetic rate, chlorophyll content, camptothecin content and so on. The results indicated that with the increase of nitrogen level, the photosynthesis, phosphorus and camptothecin content in C. acuminata leaves initially increased then decreased. Photosynthetic rate and phosphorus element content were the highest in the fertilizering amount of 30 g per plant, and camptothecin content was the highest in the fertilizering amount of 20 g per plant. Chlorophyll and nitrogen content, along with the increased nitrogen levels showed a gradual upward trend, and they were the highest in the fertilizering amount of 50 g per plant. Potassium content with the increasing nitrogen level gradually decreased, it was the lowest in the fertilizering amount of 50 g per plant. Camptothecin yield per plant in the fertilizering amount of 30 g treatment was the highest, the control(N0)was the lowest. Based on a comprehensive analysis of all indicators, we suggested that the right amount of nitrogen levels(30 g per plant)would improve the C. acuminata photosynthetic rate and promote the accumulation of nutrient elements in the leaf, thus contributing to the biosynthesis of camptothecin.