Abstract: Using K₂CO₃ as the activating agent, Camellia oleifera shell(COS) was used as the raw material to prepare COS-based activated carbon through activation in both air and nitrogen atmospheres. The effects of activation temperature, activation time, and K₂CO₃ impregnation ratio(mL ∶ g) on the preparation of activated carbon were investigated. The activated carbon was characterized using elemental analysis, Fourier-transform infrared spectroscopy(FT-IR), scanning electron microscopy(SEM), and other methods. The results showed that with an impregnation ratio of 1. 5, temperature of 800 ℃, and carbonization activation time of 1 h in air atmosphere, the obtained activated carbon had the yield of 12.48%, specific surface area o f 1 080. 94 m²/g, and methylene blue(MB) adsorption value of 441. 62 mg/g. When activated in nitrogen with impregnation ratio of 2. 5, temperature of 800 ℃, and carbonization activation time of 1 h, the obtained activated carbon had the yield of 18. 00%, specific surface area of 942. 42 m²/g, and MB adsorption value of 428.77 mg/g. The results of elemental analysis showed that activated carbon prepared under a nitrogen atmosphere had a lower H/C elemental ratio and the aromaticity was improved. FT-IR and SEM analysis indicated that activation promoted the thermal decomposition of —CH and —COOH groups and the growth of pores in the activated carbon. Compared to the samples prepared under a nitrogen atmosphere, activated carbon produced by air as pyrolysis had more developed pores and better adsorption performance.