Because of the rapid growth of the Internet, informationization in enterprises of almost all fields is growing fast. Efficiently developing high quality, easy-maintenance enterprise business information system has become the trend. Due to the similarities in the function requirements of different business information systems, in order to provide efficient and quality-guaranteed services, developers of the information systems choose to use the common services provided by the third-parties to develop loose coupling system. In this way, developers can devote more energy into the building of their kernel business logic. However, facing the large number of third-party enterprises and their services, how to perform adaption and how to guarantee the quality of the services are the issues that must be addressed. In this paper, a common service access and integration (CSAI) method for the business information systems is proposed. CSAI integrates all the common services provided by the third-party enterprises, and provides a customizable integrated common service infrastructure. The infrastructure has a uniform, interoperable, quality-guaranteed interface and provides guaranteed services and service operation supporting capabilities for different enterprises and enterprises in different fields. Detailed explanation of the functions, structure of CSAI, are provided. And a common service integration flow abstract description language that can be used for system description and development is proposed. Practical instances are used to assist our analysis.