The preface mainly explains the purpose of writing, introduces related concepts and definitions, outlines the scope, and briefly explains the current situation or focus of debate of related topics, so that readers can have a preliminary outline of the problems to be described in the full text. Content: The embryonic form of internal control has a long history, and its enrichment and development are based on the increasingly large-scale enterprises strengthening management internally, meeting social needs externally and deepening theoretical research. So far, the development of internal control theory has gone through four courses, namely, internal containment before the 1940s, internal control system from the late 40s to the 1970s, internal control structure from the 1970s to the early 1990s, and comprehensive internal control framework since the 1990s. The Comprehensive Framework of Internal Control was issued by COSO (Anti-False Financial Reporting Initiation Committee) in September with the number 1992, which is the most comprehensive description of internal control so far. The report defines internal control as: "a management method jointly formulated by the board of directors, management department and other personnel of an accounting entity to provide reasonable guarantee for the effectiveness and efficiency of enterprise operation, the reliability of financial report and the compliance goal of implementing various laws and regulations." Good internal control aims to achieve the following objectives, so as to play its corresponding role: to protect the safety and integrity of assets and prevent fraudulent mistakes; Ensure that accounting records are correct and reliable; Provide reliable financial information in time to meet the decision-making needs of enterprise managers and external stakeholders; Ensure to increase profits and reduce unnecessary expenses; Avoid risks; Prevent mistakes and abuses, and avoid or reduce losses caused by mistakes and anomalies; Ensure that the authorized responsibilities are clear and carefully performed; Ensure that the management authorities fulfill their legal responsibilities; Reduce the audit cost. Based on the important role of internal control, strengthening internal control has become a prerequisite for enterprises to improve management efficiency and win in the competition. With the establishment of China's socialist market economy system and modern enterprise system, the weakness of China's enterprise internal control has undoubtedly been exposed, and the internal control of enterprises is imperfect and unreasonable; Problems such as lax implementation of internal control and poor effect are placed in front of enterprises. The weakness of internal control has affected the survival and development of enterprises. It is urgent to strengthen the internal control of enterprises and restrain improper behavior.