This paper presents a High Availability Application Service Platform (HAASP) and analyses its high availability. The architecture of this platform contains application server platform and high availability architecture. Application server platform consists of three major components, application release platform, which is implemented with WebLogic and WebSphere cluster, application and database platforms, which are built with Oracle RAC, and IBM Domino cluster. High availability architecture is constructed by virtual machines, distributed switches and storage pools. It employs virtualization technology to integrate physical servers and storages, where physical servers are responsible for the creation of virtual server cluster, distributed switches, storage pool and management of storages. Application server platform runs on the high availability architecture and our experiment result shows that HAASP, as a scalable and flexible architecture, could offer more persistent service compared with traditional application service platforms.