Firstly, based on analysis of the main characteristics of urban rain floods and water pollution in high-density cities. On this basis, the current practical difficulties faced by disaster management are deeply analyzed. Systematically reviewing and clarifying the current research status and shortcomings about the urban flooding and water pollution were reviewed and clarified systematically. Thus further proposing effective approaches to cope with disasters. The results show that to deal with the short emergency response window period and tight physical space for urban floods, and difficulty improving efficiency for water pollution, it is necessary to establish the concept of collaborative management for urban floods and water pollution, key research and development rapid forecasting and wise scheduling for urban floods, and simultaneously research the restoration and function enhancement for river ecosystem. Keywords: high-density city; urban rain flood; urban water pollution; rain floods and water pollution co-governance; water security 〖FL