In order to construct a controlled release system of drugs and to reduce toxic side effects of 5-fluorouracil (5-FU), the novel ramose chitosan-based-5-fluorouracil (CSFU) was synthesized by a two-step method. First, ramose N,N-dicarboxyethyl chitosan (CECS) was efficiently synthesized from chitosan (CS) through microwave irradiation under mild alkaline media. Second, under the catalysis of EDC/NHS and using 5-Fu as a model drug, 1,3-bis(hydroxymethyl)-5-fluorouracil (HMFU) was successfully linked to the ramose CECS. CSFU was characterized by IR spectrum, Raman Spectrum, and UV spectrum. The influence of microwave irradiation time on degree of substitution (DS) of CECS was studied. The content of 5-FU in CSFU and its in vitro release capability in phosphate buffer solution (PBS) were determined by UV spectrum. Results showed the drug loading (DL) was 10.6% and its zeroorder release time could sustain 42 h almost without burst release, which indicated its promising application as a potential prodrug in cancer treatment.