Abstract: The objective of this experiment was to explore the effects of biochar and nitrogen application on nitrogen accumulation and translocation of leaves, seed yield and quality of tree peony. The field experiment was conducted with three biochar levels, 0 (B₀), 1 kg·m^-2(B₁), 2 kg·m^-2(B₂) applied, and three nitrogen application rates, no nitrogen application (N₀), 40 g·m^-2(N₁), 60 g·m^-2(N₂) employed. There are in total 9 treatments, including B₀N₀, B₀N₁, B₀N₂, B₁N₀, B₁N₁, B₁N₂, B₂N₀, B₂N₁ and B₂N₂. The results showed that the biochar and nitrogen fertilizer application increased the contents of protein N and non-protein N in leaves at different stages, as well as the N translocation from leaves to seeds and the N accumulation in seeds. N translocation from leaves to seeds and the N accumulation in seeds under B₁N₁ increased by 27.6% and 27.1%, respectively, compared with B₀N₀. Greater 100-seed mass and seed yield were obtained under B₁N₁ and B₂N₁, respectively, and increased by 13.6% and 16.4% compared with the B₀N₀. No significant difference was found among B₁N₁, B₁N₂, B₂N₁ and B₂N₂ when it came to yield per plant. The higher contents of protein N and total amino acid in seeds were obtained under B₂N₁ and B₁N₂ respectively, increased by 29.3% and 36.2% compared with B₀N₀. The biochar and nitrogen application increased the contents of total fatty acid and unsaturated fatty acid in seeds, and the higher content of total fatty acid was obtained under B₂N₁, increased by 17.4% compared with B₀N₀. The biochar and nitrogen application could increase the N accumulation in leaves and the N translocation from leaves to seeds, the seed yield and the contents of protein N, amino acid and fatty acid. The biochar input of 1 kg·m^-2 and the nitrogen fertilizer input of 40 g·m^-2 could lead to better results.