ABSTRACT The Capability Maturity Model Integration, (CMMI) has been officially announced in 2002 by the Carnegie Mellon® Software Engineering Institute (SEI). The SEI¡¦s core purpose is to help organizations continuously carry on to improve their flow of software engineering capabilities and to appraise the maturity rank of contractor's organization. CMMI has provided an elastic framework to practice for the software project and to ensure the software quality. Due to CMMI does not limit the method of practice, but only defines the goal which must be achieved. Therefore, the different technique, organization, and work domain all may according to their characteristics to adjust their flow to comply with the CMMI requirement. Meanwhile it has already been generally valued and adopted by both of domestic and foreign companies. At present, there are 24 domestic companies have obtained the CMMI authentication. At the same time, the Government wants to promote the competitiveness of domestic software industry to the global information service market. During CMMI¡¦s promotion, she has aggressively offered all kind of policies and estimates to invest about seventy millions new Taiwan Dollars every year with the expectation to impel 50 third level of authentication in 2007; to achieve 100 third level in 2010 as well as 5 fifth level to encourage the domestic software organization to obtain the CMMI authentication. Obviously the software quality is now one of the key impetus of Taiwan industry and more over the most important development tendency and the critical technology to increase international competitive strength of Taiwan software industry in the future. The software flow improvement is the enterprise to guarantee the quality of their provided service/product. It is an important investment of competitiveness promotion which will involve the interference of the transformation of organization, the resistance of inside and outside staff etc., hence the organization must to have the commitment of policy, the intense attempt and the motive to invest the essential resources to determine the execution of software flow improvement, thus to guarantee the success of the software flow improvement. By analyzing the implemented benefits and the various difficulties of initial stages and common bitter experience in each domain flow of the 24 domestic CMMI certificated companies to make the case study of CMMI implementation to offer the reference templates of domestic enterprises which are now complying with CMMI or those plan to induct CMMI in the future. This research analyzed the substantive benefits of the domestic 24 CMMI certified companies from the six performances, such as customer, finance, the quality, the flow, the organization and the staff after carry out CMMI. We found the mostly positive confirmation after CMMI implemented. Yet comparing the performance of finance and the staff, with approximately 50% thought it revealed less distinguished deviation in either enhancing "the capability of commercial negotiation of project taken¡¨ or decreasing the bustle of team member after CMMI carry out. This article referred to the lesson learn of domestic enterprises which got the CMMI authentication inducting A + technology which was inducting CMMI and the local consultancy companies to collect the 35 usual problems of the 4 aspects of in the staff, the force team, the inside and outside resources, and the environment of organization. Also to procure 18 bitter experiences of domain flow of both maturity second level (ML2) and third level (ML 3) in specific tasks with the common troubles in general practices of A+ technology, as well as the difficulties in particular tasks under execution, then to analyze the change tendency of the various stages of CMMI to accumulate the valuable experience assets of the domestic enterprises to implement CMMI. In this research integrated the motives; the purpose; the flow and invested resources; the key successful factors; the frequent troubles and the solution, including the concrete effectiveness and the future plan of the 3 examples to be the important reference model for those enterprises are to conduct CMMI authentication and to effectively create the systemized software development / maintain flow to promote the project productivity, the competitiveness of organization and software quality. Keywords : CMMI (Capability Maturity Model Integration); The Improvement of Software Flow; Benefit appraisal