The work aims to investigate the effects of chitosan-Cryptococcus laurentii yeast bioactive film coating treatment on disease resistance, preservation and quality of grapefruit during storage. With ''Rio Red'' grapefruit as the experimental material, harvested grapefruit was soaked respectively with 10 g/L chitosan, fermentation broth of Cryptococcus laurentii yeast (1×107 CFU/mL) and chitosan-Cryptococcus laurentii yeast complex solution for 3 min. A deionized-water-treatment group was set as the CK group, and then they were stored at room-temperature conditions (temperature:(20±2)℃, relative humidity:85%-90%). Quality indicators of fruits during storage such as disease incidence of fruits, chitinase and β-1,3-glucanase activity of peels, weight loss of fruits, color and nutrient quality were determined during storage. The best way of preservation was analyzed through the comprehensive principal component scoring method. During the storage at room temperature, the disease incidence and diameter lesions were effectively reduced in grapefruit through the treatment of chitosan, Cryptococcus laurentii and chitosan-Cryptococcus laurentii compared with the CK group. The activity of fruit peel resistance defense enzymes was enhanced to a certain extent after different treatments. These treatments also exhibited excellent preservation effects, such as the inhibition of weight loss, the enhancement of peel brightness and the delaying of nutrients loss. Among these treatments, with chitosan-Cryptococcus laurentii complex solution, the best postharvest quality of fruit was maintained. The results of principal component analysis showed that the comprehensive score of grapefruit storage quality was in the following order:chitosan-Cryptococcus laurentii composite film > CTS film > Cryptococcus laurentii film > CK film. Chitosan-Cryptococcus laurentii bioactive film treatment has the best effect on the disease resistance and preservation of green mold of harvested grapefruit, which can significantly reduce the incidence of disease and maintain fruit storage quality.