Abstract: In order to conduct a dynamic analysis of the microbial community structure of the pre-chilled water and chicken carcass during the pre-chilling process of broiler slaughter, and study the growth and decline of the two dominant floras. The TVC in the first-order, second-order pre-chilled water and chicken carcasses were detected, when the first batch of slaughtered chicken passed pre-cooled water for 0, 2, 4, 6 and 8 h. Subsequently, a high-through put sequencing method was used to dynamically analyze the community structure of them. The result of the determination of the total number of colonies showed that during the pre-cooling process, the TVC in the first-stage, pre-cooled water increased from 10³ CFU/mL to 10⁵ CFU/mL, and the TVC in the second-stage pre-cooled water increased from 10² CFU/mL to 10⁴ CFU/mL. Before pre-cooling, the total number of colonies in chicken carcass was 4.53 lg CFU/g, after pre-cooling, the total number of colonies on the surface of the chicken carcass was higher than that before the pre-cooling within 6 to 8 hours, indicating that the pre-cooling water had lost the effect of cleaning and reducing bacteria, and might also cause cross-contamination of the chicken carcass. High-throughput sequencing found that during the pre-cooling process, the genus of Aeromonas in the first-stage pre-cooling water decreased, while the genus of Pseudomonas and Streptococcus increased; the genus of Acinetobacter in the second-stage pre-cooling water decreased, Pseudomonas increased; compared with before pre-cooling, Vagococcus and Weissella of the chicken carcass decreased, and the Chrysobacterium and Pseudomonas increased during the pre-cooling process. This study showed that the pre-cooling process had a better bacteria-reduced effect on Aeromonas, Vagococcus and Weissella, but had a poor reduction effect on Chrysobacterium and Pseudomonas. This provided a reference for the optimization of the chicken carcass pre-cooling process after slaughter, and at the same time provided a guarantee for the quality and safety of chilled chicken products.