Community Study"has already had a history of about 150 years. Community countermeasure for disaster prevention and mitigation is a integrated problem of science. It is very important to fully mobilize the disaster prevention and mitigation functions of communities. It has a great significance in the strategy of China’s modernization and sustainable development to determine the optimal community countermeasures for disaster prevention and mitigation. It is a development direction of significance for system science or Complexity Science to deal with the problems of community countermeasures for disaster prevention and mitigation using the theory and models of Complexity Science. In the present paper

four scientific and technological problems in the study of community countermeasures for disaster prevention and mitigation have been raised and analyzed

that is

how should the role and direction of emergency management of community disaster prevention and mitigation be defined?What is a safe community in disaster prevention and mitigation?How can an abrupt disaster event be warned in advance?How is a community disaster prevention and mitigation system selforganized?The theory of Complexity Science has been introduced to study the community disaster prevention and mitigation. A theoretical framework has been discussed for application of Complexity Science in the community countermeasures for disaster prevention and mitigation. System control countermeasures

system organization countermeasures

sytem decisionmaking countermeasures and system evolution countermeasures are studied and discussed.