当前，公共危机预警工作越来越受到世界上各个国家危机管理机构的重视，及时有效的进行公共危机预警被视为提高危机管理效率和水平的必要条件。将基于案例推理（Case-based Reasoning,CBR）的Web式系统及其相关技术应用到公共危机预警实践中，可以改善当前危机管理部门在进行决策时信息不对称的状况，扭转危机预警工作中社会参与程度低的不良局面。这对于实现科学化的公共危机管理有重要的意义。 本文首先通过阐述我国与国外公共危机预警工作的模式，深入了解我国公共危机预警工作的现状，分析并总结我国在这方面中存在的不足之处，揭示了我国危机预警机制建设中应该改进的问题。通过对我国最近几年来以及近来发生的一系列公共危机事件的学习和研究，明确了本系统的功能需求；并根据其对半结构化和非结构化的决策问题能够有效解决的能力，决定使用基于案例推理作为本系统的推理方法并结合B/S结构建立解决当前我国公共危机预警工作中面临的难题。 在对前人对公共危机预警研究和对我国近来发生的一系列公共危机事件研究分析的基础上，本文深入研究了基于案例推理的Web式公共危机预警系统的关键技术，包括危机案例库的构建（构建包括案例的表达、案例库的索引策略和案例的存储）、危机案例的检索、重用、修改和学习。在此基础上开发出了公共危机预警系统的原型系统，详细介绍了中文检索系统中分词的处理方法，提出了较为合理的检索算法，并按照可靠性原则对危机预警系统进行可靠性的分析和计算。 最后，本文对前面所研究的内容和结论进行了总结,并对Web式预警系统做了初步的应用分析,以及对公共危机预警系统后续研究进行展望。

Presently, crisis management institutions around the world increase emphasis on the work of the public crisis forewarn. it is regarded as a necessary condition for improving the efficiency and the level of crisis management to carry out the public crisis forewarns timely and effectively apply the Web type system based on Case-based Reasoning(CBR) and the correlation technique of public crisis forewarn in the practice, may improve the condition of the information asymmetrical when current crisis management department carries on the decision-making, and reverse the Unfavorable situation of social participation degree low in the work of crisis forewarns. It has a vital significance to realize the scientific public crisis management by this doing. Firstly, this paper elaborated the work patterns of the public crisis forewarn about our country and the overseas, inquire into the present situation of our country’s public crisis forewarns work, analyzes and summarizes our country the deficiency which exists in this aspect, then revealed the question where our country’s crisis early-warning mechanism should improve. Through a series of public crisis event’s study and research as well as recently occurs in our country for several years, it has been clear about this system's function demand and According to the ability on the semi-structured and the non-structured decision-making problem, the paper decide to solve the problem that faces in the present work of public crisis forewarn by the Case-based Reasoning method and unifies the B/S structure system. Then, in the foundation of study and analyze a series of public crisis events recently occurs in our country by the predecessor, the paper deeply researched crisis early-warning system which based on the Case-based Reasoning method, including the crisis case’s storehouse's construction (case expression, case storehouse's index strategy and case memory),the crisis case's retrieval、modify and learning. And developed the public crisis early-warning system's prototype system based on this, introduced the participle processing method of Chinese retrieval system in detail, proposed the more reasonable searching algorithm. In the last, to carry on the reliable analysis and computation on the crisis early-warning system deferred to the reliable principle. Finally, the paper made a conclusion with the content which has studied already, and made a preliminary analysis to the Web type early-warning system, as well as carried on the forecast to the public crisis early-warning system’s following research.