Yellow blotch disease (YBD) is a bacterial disease that seriously affects the yield and quality of Pleurotus ostreatus. The samples of YBD were obtained from several main production areas of P. ostreatus in Shanxi province. The pathogenic strain HB-1 was isolated from YBD samples, and further determined by morphological observation, molecular identification and physiological and biochemical profiles. The results showed that the pathogen was identified as Bacillus amyloliquefaciens , which was different from Pseudomonas tolaasii, a recognized pathogen of P. ostreatus YBD. Furthermore, the biocontrol effect of Acetobacter fermentation broth on the pathogenic strain HB-1 was investigated. The results indicated that the fermentation broth of Acetobacter BA15 fermentation broth had a significant inhibitory effect on the pathogenic strain HB-1. The results of this study provide a reference for identification and biocontrol of YBD pathogens in P. ostreatus.