Abstract: In recent years, abrupt environmental pollution accidents occurred frequently in China, having resulted in huge hazards on socio-economic development. Through structured hierarchical storage and searching technology based on case reasoning, the emergency management application case library can be established, with which historical matching cases can be found by quick search, and then relatively optimal solution tools can be provided for the policy makers. The realization approaches of information database based on case-reasoning retrieval technology were explored. The contents of the case library were researched, the structure was designed and the system developed. Finally the case retrieval system of abrupt environmental pollution accidents based on Web technology was established, which included more than 500 cases. The system takes the nearest neighbor decoding to search similar fitting cases, possessing retrieving, correcting, studying and statistical analysis functions and so on. It can provide references for the emergency response to the newly happened abrupt environmental accidents.