Abstract: Objective:Wax apple fruits(cv. Daye)were used to isolate pathogen which could cause soft rot disease of the fruit,its antagonistic microorganisms were screened and the mechanism of antagonism was explored. Methods:Conventional tissue separation method was applied to separate disease tissue. And the antagonistic microorganisms were screened by the flat-stand method. The pathogen and antagonistic microorganisms were identified by morphological and molecular biological methods. The mechanism was explored by spatial competition and resistance-related enzyme activity assays. Results:A total of 143 antagonistic strains were isolated. The strain which had the most obvious effect was named D-1,of which the diameter of bacteriostatic circle was 11.10 mm and the strain was identified as Bacillus safensis. In addition,in vivo test showed that antagonistic strain D-1 could effectively inhibit the development of lesions and reduce the disease incidence,it could colonize quickly at the wound to present space competition with pathogen. Furthermore,D-1 significantly increased the activity of phenylalanine ammonia lyase,peroxidase and polyphenol oxidase,and improved disease resistance against soft rot of wax apple fruit.