Coupling water soluble and biodegradable poly( N (2 hydroxyethyl) L glutamine)(PHEG) synthesized from poly(( γ benzyl) L glutamine) and 2 aminoethanol with 5 fluorouracil 1 acetic acid(FUA) as a simulated drug affords a polymer prodrug poly( N (2 hydroxyethyl) L glutamine) 5 fluorouracil 1 acetic acid(PHEG FUA). The conjugation between the polymer and the drug compound has been confirmed by IR, UV, 1 H NMR and DSC. The content of 5 fluorouracil was determined to be about 26%(UV method). The in vitro test results show that the accumulated drug release amounts of PHEG FUA was 47 63% in phosphorus salt buffer solution(pH=7 2) during 120 h, indicating the conjugated compound has an obvious sustained release effect.