Abstract: Citrus blue mold (CBM) caused by Penicillium italicum is the most harmful postharvest disease of citrus fruits. In order to obtain an effective citrus endophytic fungus strain which can be used for the control of citrus blue mold, series of experiments were conducted including the isolation of endophytes from citrus fruits, in vitro and in vivo screening of the effective endophytic fungus, identification of the endophytic fungus through morphology and multilocus phylogenetic analysis, control efficacy and functional characteristics of target strain against CBM, and the stability and control efficacy of metabolites from the target strain. The results showed that citrus endophytic fungus Gds-1 had the priority in P. italicum suppressive efficacy both in vivo and in vitro and it was identified as Fusarium avenaceum by multilocus phylogenetic analysis. Application of Gds-1 mycelium had a good preventive effect against P. italicum, with the best efficacy in Pre-48 h application (90.67%). F. avenaceum Gds-1 could not damage the intact citrus epidermis, but it could expand and suppress P. italicum in the wound or infected tissues of citrus epidermis. Gds-1 culture filtrates could with stand extreme temperature(−80 ℃-100 ℃) and unpleasant acid-base changes (pH=5-10), which had an effective and stable antagonistic effect against P. italicum. At 28 d and 56 d, the control efficacy of Gds-1 culture filtrates against P. italicum was comparable to that of 100 μg/mL imazalil, which was significantly higher than that of the water control. This study is the first report of the control efficacy of F. avenaceum Gds-1 against CBM by itself or producing antagonistic biomolecules which provides an effective new source of citrus biogenic preservatives after harvest, and a new sight on biocontrol mechanism of biocontrol Fusarium.