Norovirus (NoV) infection is a major pathogen causing acute gastroenteritis (AGE) across all age groups worldwide. Here, we report on the prevalence and genetic characteristics of NoVs in patients with AGE at diarrhea clinics in Huzhou from January 2019 to October 2023. A total of 2846 specimens were collected and tested for NoV by real-time RT-PCR. Approximately 460 specimens (16.16%) were identified as Nov positive. RNA-dependent RNA polymerase (RdRp) and capsid gene sequences of 216 viral strains were amplified and sequenced, and genotyping was performed using the RIVM online typing tool. During this period, at least 20 NoV genotypes were observed, with GII.4 Sydney being the most predominant. Phylogenetic analysis of selected strains revealed that all GII.4 Sydney[P16] strains clustered together and were closely related to strains from Beijing, Shanghai, Hangzhou, Nanjing and the United States, with nucleotide homologies ranging from 96.9% to 99.7%. Our study indicates that GII.4 Sydney is undergoing a new wave of resurgence, and becoming the main epidemic strain again, particularly when GII.4 Sydney[P16] is causing peaks in NoV positivity rates in January 2022 and October 2023. These results highlight the need for continuous long-term monitoring of GII.4 Sydney NoV variants.