ABSTRACT As an era of progress, the business size change from small to a large scale farm, the management concept also affected. Early from the Taylor and Gilbreth´time control in scientific management to the newly developed methods of human behavior and system control, Enterprise no longer used the simple way as in the production line and sales, Global business is another indication of growing. The appraisal system applied to measure the whole system but not for individual. For the sake of protecting the investor under the rapid change in the business runing, The Ministry of Finance applied the internal control system designed by The Committee of Sponsoring Organizations of the Treadway Commission ¡]COSO,1992¡^as a blue print to stipulate the internal control and audit policy, and to force business in this country to follow it. This system will promote the operating efficiency as well as help to attain the goal required for business, Moreover It can assure the truth of financial report and the compliance in following the government regulation. Case company is a typical manufacturing firm, Their management model is traditional such as human resource, financial, quality control, and manufacturing management , Each system have its own discipline in order to achieve their target. However, Internal control will join the above management procedure as a whole, also set up some monitoring system for leading all the managemental activities to obtain the required aim and to correct the great error that might be happened in the enterprise. This paper will point out the difference in performance after introducing the internal control system, and select two critical cycles as example .