Tourism public opinion always significantly stimulates group sentiments through social media, especially the negative sentiments that will bring destructive effects. However, the influence of online review negativity dominance on tourism public opinion in social media remains unexplored. This study analyzes the roles of residents and tourists in spreading negative sentiments and their impact pathways on tourism public opinion intensity from psychological and geographical perspectives, integrating negativity bias theory and social distance theory. This study selected the Ningxia public opinion event as a research case and collected a total of 222016 valid user comments by crawling TikTok data from March 15 to April 10, 2024. The data analysis results found that resident negativity dominance positively predicts negative sentiment contagion among tourists and significantly escalates tourism public opinion intensity. Moreover, the degree of negative emotional contagion among tourists mediates the relationship between resident negativity dominance and public opinion intensity. Theoretically, this study contributes to negative emotional spreading from an information source perspective, distinguishing the mechanisms of regional groups in public opinion. Practically, this study proposes the critical role of residents in tourism public opinion governance, reducing resident negative reviews to prevent the escalation of tourism public opinion.