Urea-Functionalized chitosan (Cs-Pr-Urea) was prepared and characterized using different spectroscopic, microscopic and analytical methods or techniques. The Cs-Pr-Urea modified polymer was used, as a new biopolymeric and efficient bifunctional catalyst, for the synthesis of pyrimido[4,5-b]quinoline-2,4-dione derivatives in aqueous ethanolic media. In this regard, some of the heterocyclic pyrimidine derivatives have been synthesized by through four-component reaction of barbituric acid condensation, aldehyde derivatives, specific amines and dimedone in EtOH/H₂O under reflux conditions , efficient and efficient manner, with the reaction. This method has the prominent features such as green solvent, high to quantitative yields of the favorable products, easy product separation, no purification with chromatography column, heterogeneous catalyst and easy recyclability of catalyst. In this methodology, the ideal conditions for the reaction are shown.