In order to explore the effect of pyrolysis temperature on the adsorption of ammonium nitrogen(NH4+-N)by biochar and improve the NH4+-N adsorption performance of biochar，this experiment used a large amount of agricultural and forestry abandoned Schima superba branches as raw materials. Three different pyrolysis temperatures of 450，550，and 650℃ were set up，named as T450，T550，and T650，respectively. The NH4+-N adsorption capacity，NH4+-N desorption capacity，and cation exchange capacity(CEC)of biochar were measured to further evaluate its adsorption performance. Additionally，the physical and chemical adsorption capacity of biochar was characterized by iodine adsorption capacity and methylene blue adsorption capacity，respectively. The results showed that the T450 treatment exhibited a stronger adsorption capacity for NH4+-N，which was significantly higher than that under T550 and T650 treatments. Specifically，when biochar was added to a 50 mL solution with a concentration of 500 mg/L NH4Cl，the NH4+-N removal rate of T450 treatment reached 77.8%，which was significantly higher than that of the T550(74.5%)and the T650(71.3%)treatments. Subsequently，after desorption with a 50 mL solution of 1 mol/L KCl，only 71.3% of the total adsorbed amount was desorbed from the biochar at T450 treatment，while the adsorption capacity of biochar treated at T550 and T650 treatments for NH4+-N was significantly reduced，with as much as 87.5% and 95.3% of NH4+-N were desorbed back to the solution，respectively. Correlation analysis indicated that the enhancement of NH4+-N adsorption performance by biochar was significantly positively correlated with CEC and methylene blue adsorption capacity. In contrast，it showed a significantly negative linear relationship with iodine adsorption capacity. Specifically，the CEC and methylene blue adsorption capacity of T450 treatment were significantly higher than T550 and T650 treatments(P<0.05). However，the biochar treated with T550 and T650 showed higher iodine adsorption. In practical application，the removal rate of NH4+-N in rivers by T450 biochar with strong NH4+-N adsorption capacity reached 48.2% within 30 hours. In summary，increasing the pyrolysis temperature can reduce the ion exchange capacity and chemical adsorption of biochar，which is not conducive to the adsorption of NH4+-N. If the goal is to enhance the adsorption performance for NH4+-N，preparing biochar at 450℃ is a more advantageous choice compared to 550 and 650℃.