Because of the development of the information technology, the enterprises of telecommunication introduce many applications system which have different independent function or some software developed by enterprises itself. After enterprises introduce these systems, they find information systems ongoing to expand have influenced the performance of systems and the operation time of users. Even influence the customer service satisfaction. Thus the enterprise continually to integrate system functions. At the same time, they find these independent systems have many problems, such as valuable data have been input several times to different system, data and object standard different between different systems. The technology of enterprise application integration¡]EAI¡^ provides enterprise a better solution to solve these problems. The purpose of this study is to address the issue of telecommunication system integration and using the EAI¡¦s methodology to analysis system. The analytics contains 3 modules, i.e. ¡§data¡¨, ¡§activity¡¨ and ¡§process¡¨ that handle functions of data transforming, message dispatching and process modeling among the heterogeneous systems. This study will use three modules of EAI to analyze the operation information system and study the main evaluation factors of EAI. This study could be submitted to the telecommunication industry for presetting construction when they consider to implementing the ¡§Enterprise Application Integration¡¨ system.