With the development of metropolitan regions and the appearance of urban agglomerations, cities have been more closely related. For the restricted emergency rescue resource in a single city, it has become more and more imminent for the demand of the intercity collaborative resistance to major accident, so as to improve the protection capacity of urban security. In order to find an effective intercity emergency rescue collaborative system, this paper introduces the concept and analysis method of ecosystem theory into intercity emergency rescue. Based on the analysis of the formation-process of emergency rescue individual, population and community, a three-level intercity emergency rescue collaborative system is constructed according to the characteristics of dynamics and structure of intercity emergency rescue ecosystem, then the collaboration mechanism of information, resource and process in the intercity emergency rescue ecosystem is also studied in this paper, so as to offer available strategy and method for the ecosystem theory applied to intercity emergency rescue. Through the studies of intercity emergency rescue eco-system, it illuminates that the proposed emergency system can not only cope with the major accident more timely and effectively, but also integrate the intercity information resources and emergency rescue resource and process optimization. With the development of metropolitan regions and the appearance of urban agglomerations, cities have been more closely related. For the restricted emergency rescue resource in a single city, it has become more and more imminent for the demand of the intercity collaborative resistance to major accident, so as to improve the protection capacity of urban security. In order to find an effective intercity emergency rescue collaborative system, this paper introduces the concept and analysis method of ecosystem theory into intercity emergency rescue. Based on the analysis of the formation-process of emergency rescue individual, population and community, a three-level intercity emergency rescue collaborative system is constructed according to the characteristics of dynamics and structure of intercity emergency rescue ecosystem, then the collaboration mechanism of information, resource and process in the intercity emergency rescue ecosystem is also studied in this paper, so as to offer availabl Through the studies of intercity emergency rescue eco-system, it illuminates that the proposed emergency system can not only cope with the major accident more timely and effectively, but also integrate the intercity information resources and emergency rescue resource and process optimization.