The invention discloses a guarantee method and system for high availability of a virtual instance of an electric power system. The method comprises the following steps of step 1.initial configuration;step 2.real-time environment monitoring; step 3.streaming message communication; step 4.quintuple model analysis and judgment; and step 5.virtual instance migration. The system comprises an initial configuration module, a real-time environment monitoring module, a streaming message communication module, a quintuple model analysis and judgment module and a virtual instance migration module. According to the method and the system, the continuous operation of front-end access of an application system in a cloud environment is guaranteed; the system can scan actively; when a fault of a physical device is discovered, the system analyzes according to a quintuple model and judges whether the fault makes a fatal impact on the system operation; and when the system judges that the fault can affectthe operation of the virtual instance of the application system, the system starts a virtual machine migration and recovery mechanism, so that the continuous front-end access of the virtual instance of business is guaranteed.