Water-soluble biomimetic chitosan derivative conjugating zwitterionic phosphorylcholine was efficiently prepared through Atherton-Todd reaction under the mild conditions, and the possible formation mechanism of zwitterionic product was related to the nucleophilic attack of adjacent 3-hydroxyl on the D-glucosamine residue to phosphorus with the help of base. UV absorption and melting behaviors of DNA/phosphorylcholine-bound chitosan derivative showed that the phosphorylcholine-bound chitosan derivative could be a new carrier for long-circulating macromolecular drug delivery.