In modern society, social media has become an important platform for individuals to express themselves and communicate their thoughts and emotions, which profoundly affects our perception of the sense of meaning in life and the spread of positive psychology. The research design for theme identification and sentiment analysis based on social media data includes five steps: data collection, data cleaning, TF-IDF calculation, theme clustering, and sentiment analysis. In this paper, we take the “Xin Guan epidemic” as a case study to identify the core topics of discussion on the sense of meaning of life and assess the sentiment tendency of users under these topics so as to reveal the influence of the perception of the sense of meaning of life on the dissemination of positive psychology on social media. A total of 11 topics related to the sense of meaning of life were obtained from the microblogging platform, and each topic effectively promoted the positive psychology of social media users. It is shown that the perception of the meaning of life is positively related to the spread of positive psychology.