Abstract: 【Purpose/signficance】Through the extensive collection of Weibo data, we can deeply explore the changing trend of public sentiment in different stages, so as to provide empirical support for the formation of effective communication strategies and social inter⁃ vention【. Method/process】Applying BERTopic and SnowNLP to achieve theme emotional fusion analysis, through the analysis of the new crown vaccine public opinion content in the early stage of the new crown outbreak, the early stage of the marketing and the early stage of the liberalization policy, the theme modeling results of each stage and the emotional score under the corresponding text are ob⁃ tained【. Result/conclusion】The theme modeling results found that the public's focus shifted from "vaccine response and vaccine re⁃ search and development" to "vaccination matters", and finally to "optimizing epidemic prevention policies"; In terms of emotional analysis, the public's attitude towards the theme of "new crown vaccine" is more positive, but there is also a little neutral and negative attitude under some specific themes【. Innovation/limitation】The study creatively explored the public opinion of COVID-19 Vaccine’s theme-emotional evolution under the three time dimensions, but the existing analysis is only for a single social media platform, and will expand the research sample and further explored from multiple perspectives.