The internal control system plays an important role in the operation of the enterprises, because it is the important means by which the enterprises use to strengthen management and improve the economic efficiency. However, our country’s study about the subject began in the 80's of last century, which was 40 years later than that of Western countries. In addition, the internal control system of some Chinese enterprises has been always loose, and some enterprises even do not have the scientific internal control system.The introduction of the new accounting standards in the year 2006 has brought a challenge for the construction of our country’s enterprises’ internal control. For a long time, China's enterprises carry on the internal control under the management of accounting system. So the implementation of new accounting standards indicates that the enterprises must be in accordance with their own actual conditions to build the accounting system. As for the establishment of their own accounting system, China's enterprises do not have enough experience. So in such circumstance, how to improve and enhance the enterprise's internal control is a pressing need.The oil companies in southwest are the most outstanding throughout the country in terms of engineering technology and management. In this article, I will carry out a deep research in one oil company, which is an effective means of studying internal control, in order to have a good knowledge of its internal control. Then I will summarize and promote the integrated parts it has done normatively, as well as bring forward some suggestions for improvement concerning some of its existing problems.
Key words: Internal Control Investigation and Analysis Accounting system