Tea polyphenols (TPs) could prevent obesity by regulating gut microbiota. However, it is unclear how TPs play this regulatory effect during the development of obesity. To reveal the dynamic changes in gut microbiota, obese mice were induced with a high-fat diet (HFD) and intervened with different doses of TPs for 8 weeks. The results showed that HFD continuously altered gut microbial composition and induced an increase in the Firmicutes/Bacteroidetes (F/B) ratio, resulting in gut microbial dysbiosis and obesity. TPs intervention improved the increase in F/B ratio and regulated the dysbiosis caused by HFD. This regulatory effect was related to its dose and intervention time, among which the effects of daily 200 mg/kg bw TPs intervention for 8 weeks was the best. Random forest and network analysis results indicated that TPs could continuously increase the relative abundance of prevent-obesity bacteria (such as Akkermansia, Lactobacillaceae, and Alistipes), decrease the relative abundance of promote-obesity bacteria (such as Lachnospiraceae, Oscillospiraceae, and Ruminococcaceae), and enhance the gut microbial network complexity. Consequently, TPs could affect lipid accumulation and prevent obesity development. The study provides new insights into the mechanism of TPs anti-obesity.