The rapid spread of network public opinion during emergencies poses significant threats to public life and social stability. This study constructs an analysis model for emergency network public opinion propagation based on information ecology theory, adopting a three-dimensional perspective of “information-information subject-information environment”. Taking the Henan severe flooding event as a case study, we conduct in-depth analysis of content characteristics, user characteristics, and emotional characteristics across different lifecycle stages. We then examine the dynamic evolution patterns from an ecosystem perspective and summarize the dissemination characteristics of emergency network public opinion. The research demonstrates that the information ecology-based analysis model provides a comprehensive framework for understanding public opinion propagation patterns and characteristics. The three-dimensional interactions among information, information subjects, and information environment drive the dynamic evolution of public opinion, offering strategic insights for emergency network public opinion management.