The synthesis of phosphorylated Achyranthes bidentata polysaccharide (P-AbPS) was reported based on different strategies. The P-AbPS with high degree of substitution (D.S.>0.5) was obtained when phosphorus oxychloride (POCl 3) was used as a phosphorylating agent and trimethyl phosphate-pyridine or dimethyl formamide was used as solvent. The influences of different solvents and reaction conditions were discussed. The pharmacology assay shows that P-AbPS possesses antitumor activity against sarcoma 180 and Lewis lung cancer in mice. The synthesis of phosphorylated Achyranthes bidentata polysaccharide (P-AbPS) was reported based on different strategies. The P-AbPS with high degree of substitution (DS> 0.5) was obtained when phosphorus oxychloride (POCl 3) was used as a phosphorylating agent and trimethyl The influences of different solvents and reaction conditions were discussed. The pharmacology assay shows that P-AbPS possesses antitumor activity against sarcoma 180 and Lewis lung cancer in mice.