This paper employed an enrichment culture and isolation method to screen a bacterial strain with high ammonia nitrogen degradation capability from some cultivation ponds of Chinese mitten crab （Eriocheir sinensis）.Based on morphological， physiological & biochemical， and molecular biological characteristics， the strain was identified as the BC17 of Bacillus licheniformis. The analysis results of bacterial growth and ammonia nitrogen degradation efficiency under different environmental conditions revealed that the optimal carbon source for the strain was sodium citrate. The most effective parameters for ammonia nitrogen degradation were a carbon-to-nitrogen ratio of 15， temperature of 37-40 ℃， pH=7.0， and salinity of 0-5. Juvenile crabs with an initial body weight of （9.97±1.12）g were randomly divided into an experimental group and a control group. The aquaculture water in the experimental group was supplemented with a bacterial suspension at an initial concentration of 10⁶ CFU/mL during the experimental period of 31 days. The results indicated that the ammonia nitrogen concentration in the water of the experimental group was significantly lower than that of the control group （P<0.05）. The survival rate， growth rates of carapace length and width in the experiment group were significantly higher than those in the control group （P<0.05）， meanwhile， the weight gain rate after molting was a light higher in the experiment group compared to the control group （P>0.05）. Analysis of the intestinal microbiota of the crabs revealed reduced abundance of pathogenic bacteria such as Malaciobacter and Shewanella in the experimental group.This study demonstrates that the strain BC17 of Bacillus licheniformis not only effectively removes ammonia nitrogen and nitrite nitrogen in aquaculture waters and improves water quality， but also enhances the survival and growth performance， and suppresses pathogenic bacteria in the intestine of the Chinese mitten crab. Generally， these findings highlighted the potential application value of the strain BC17 of Bacillus licheniformis in sustainable aquaculture industry of Chinese mitten crab.