The research on the influence mechanism of hot search topics on urban communication helps understand the media power and discourse practice of urban image construction in the era of short video. Therefore, this paper takes 17 cases of Chinese hot search urban topics from 2020 to 2024 as the research object and extracts one outcome variable and seven explanatory variables on urban hot search topics based on existing literature. Through the qualitative comparison of clear sets (QCA) analysis, it is found following trending topics has become a major way and pattern of urban public opinion discourse generation on short video platforms. On the one hand, the discourse is connected by the extension of urban hot search topics, and the spontaneous expression of netizens’ demands has exceeded the topic itself and has become the public’s concern. On the other hand, institutional media and mainstream media form event characterization through macro interpretation of hot topics, which often relate to urban governance and government administration, and further affect urban communication.