With corn cob as raw material and potassium acetate as activator,potassium acetate modified biochar(CCBC)and manganese loaded potassium acetate modified biochar(Mn-CCBC)were prepared by high temperature cracking method at 800℃,and the adsorption properties on methylene blue were investigated.The results show that Mn-CCBC has more abundant pore structure and larger specific surface area,and has better removal effect on methylene blue.Under the conditions of 25℃,adsorption time 60 min and initial mass concentration 30 mg/L,the removal rate of methylene blue could reach 99.594%.