Chitosan-grafted citric acid carbon dots〔P(CS-g-CA)CDs〕were synthesized by hydrothermal reaction method using chitosan (CS), N-(2-hydroxyethyl)-ethylenediamine and anhydrous citric acid (CA) as the main raw materials.Then a series of corn starch/chitosan-based carbon dot composite light-converting films〔CST/P(CS-g-CA)CDs5,CST/P(CS-g-CA)CDs10,CST/P(CS-g-CA)CDs20〕with different P(CS-g-CA)CDs contents were prepared by flow-delaying method using corn starch (CST) as the base material.The optical properties, mechanical properties, hydrophilic properties and degradation properties of the composite films were investigated by fluorescence spectroscopy, a universal testing machine, contact Angle measuring instrument and soil degradation test. The results showed that with the increase of P(CS-g-CA)CDs, the tensile strength of the composite films increased first and then decreased, and the elongation at break showed an increasing trend as a whole; the contact angle of the composite films increased from 37.5° to 87° and the hydrophilic properties of the composite films decreased. Pure corn starch film without fluorescence response, CST/P(CS-g-CA)CDs20 can convert light in the UV region at 374 nm to blue fluorescence at 459 nm, and the composite film has blue light conversion performance. Difficult water-soluble carbon dots blending can delay the degradation of pure corn starch film, prolong the film service life, and achieve adjustable degradation rate.