Abstract: In this paper, pomelo peel was used as the material and ZnCl₂ was used as the activator and fire retardant, the pomelo peel biomass activated carbon (BAC) was prepared by high temperature pyrolysis method. The adsorption of organic dyes and formaldehyde was also studied.The results showed that BAC had obvious pores and hydrophilic functional groups of C=O, O-H, C-O on the surface when the temperature was 500℃, the concentration of ZnCl₂ was 20 g/L, the impregnation ratio was 3:1, the impregnation time was 24 h, and the carbonization time was 45 min. BAC had obvious pores and hydrophilic functional groups of C=O, O-H, C-O on the surface. The total surface area, total pore volume and the average pore size of BAC were 983.27 m²/g, 0.56 cm³/g and 2.26 nm, respectively.The kinetic of dye onto BAC followed pseudo-second-order kinetic model. The maximum adsorption capacity of methylene blue, neutral red and crystal violet onto BAC were 75.81, 96.19 and 64.06 mg/g, respectively.Based on this, the dye adsorbed by 1.0 g BAC and the adsorption rate was up to 90%. Furthermore, BAC was applied to adsorb formaldehyde and the adsorption capacity was 6.0~9.5 μg/g.