[Objective] To identify one endophytic strain longA which was isolated from healthy apple tree branches and study its antifungal mechanism. [Methods] Strain longA was identified based on the biochemical characteristics and 16S rRNA gene sequence analysis. The inhibitory efficiency of longA on the hyphal growth and conidial germination of V. mali were investigated by confrontation culture on slides. [Results] Strain longA was defined as Bacillus amyloliquefaciens. It could reduce the germination rate of spore and induce changes of mycelia morphology of V. mali significantly, such as deformity, branch increasing and cytoplasm exosmosis. Strain longA was aerobic. It could use glucose, sucrose, mannitol, lactic acid and citric acid as carbon source. Tolerates concentrations of NaCl up to 7%. Catalase reaction was positive. It could reduce nitrate, liquefy gelatin and degrade starch. It could not use citrate as the sole carbon source for growth. V-P test was negative. [Conclusion] Strain longA showed a certain potential of bio-control in the inhibition of V. mali.