Abstract: In order to support the development and integration of cooperative applications based on the research achievements of distributed object-oriented technology and group communi-cation technology，an object-oriented group communication service——GCS is designed and implemented．First，the advantages and shortages of CORBA and group communication are discussed，and the fact that they provide complementary functionality and their combination can satisfy the requirements of the cooperative application much better is pointed out．Second，the components and system architecture，as well as the implementation of GCS are described．Last，a development framework for group members to facilitate the development of cooperative applications is presented．