Rain-on-snow floods are extreme hydrological events characterized by sudden onset, low frequency, and high destructiveness, often leading to severe disasters. Due to their complex nature, understanding the disaster-causing mechanisms, evolution processes, and prevention strategies of rain-on-snow floods has become one of the most pressing challenges in contemporary hydrology and a fundamental requirement for national disaster prevention and mitigation. This study reviews the distribution characteristics and hazards of rain-on-snow floods and examines current research progress and development trends. It is found that the definition of rain-on-snow floods remains at a “potential” stage, with varying thresholds and considerable inconsistency. The disaster-causing mechanisms are still unclear, resulting in a limited understanding of flood evolution laws and a lack of robust simulation and forecasting models. These gaps hinder accurate flood warnings and risk management. There is an urgent need to establish a “real” definition of rain-on-snow floods, based on extensive flood event data and related observations. Additionally, revealing the underlying mechanisms, developing reliable simulation and forecasting models, and replicating typical rain-on-snow flood events through application-based demonstrations are essential next steps. This will enable a clearer understanding of the evolutionary processes, future changes, and potential risks of rain-on-snow floods at regional, basin, and global scales, while also supporting the development of effective prevention and mitigation strategies.