In order to optimize preparation process of reed-based biochar, base on the single factor test to examine the effects of three parameters, i.e. pyrolysis temperature, ammonia mass fraction and impregnation ratio (ratio of biomass feedstock to ammonia mass) on the adsorption performance of reed-based biochar, by the Box-Benhnken Center combination design experiment and the response surface method, the activation process parameters were optimized. The results showed that all three factors had an effect on the specific surface area of biochar, and the significant effects are:pyrolysis temperature>ammonia mass fraction>impregnation ratio. The optimum activation process parameters were the pyrolysis temperature 620℃, the ammonia mass fraction 8%, and the impregnation ratio 1:5. The surface area and iodine value of prepared activated carbon under this condition was 334.49 m²/g and 585.52 mg/g, respectively,which were better than the samples which were not optimized. The experimental and theoretical values(335.2 m²/g、582.288 mg/g)were basically consistent. The response surface model fits well with the actual situation, and the effective feasibility of the model was verified.