Abstract: 【Objective】 To isolate and obtain the antagonistic bacteria with strong antagonistic effect on the pathogen of Saprolegniasis, analyze the antagonistic characteristics of Saprolegniasis antagonistic bacteria, and discuss the biological control method in Xinjiang.【Method】In this study, the highly pathogenic fungus Saprolegnia LF04 isolated from the laboratory were used as the indicator bacteria. And the antagonistic bacteria JL50 with strong antagonism against LF04 was isolated from the body surface of the healthy carp (Cyprinus carpio). The antagonistic bacteria were identified by traditional classification and molecular identification methods, and the safety, antagonistic stability and antagonistic range of the antagonistic bacteria were tested.【Result】The antagonistic bacteria JL50 was identified as Bacillus family, Bacillus subtilis genus and Bacillus pumilus by traditional classification and molecular classification. The safety of the antagonist, the stability of the antagonism and the test of the antagonistic range were carried out. The results showed that this strain was safe for fry and increased the survival rate of the fry by 12%, and had a strong antagonism to the infection of the spore suspension of Saprolegnia. At the time of experiment 7 d, the cumulative infection rate of Saprolegniasis in the experimental group and the control group was 53.3% and 95%, and the difference was significant (P<0.05).And after 10 generations of passage, the antagonism was not weakened.【Conclusion】The antagonistic bacteria JL50 isolated from the body surface of healthy carp has a significant inhibitory effect on the growth of specific water mold and has potential development and application value in fishery biocontrol.