The article reveals the nature of a competitive enterprise, identifies the external environment factors affect the enterprise competitive position and provides insights on the enterprise economic security concept. In thus study, the essence of the enterprise economic security category is viewed as a specifically built system of preventive measures aimed at conducting targeted permanent activities to ensure sustainable efficient enterprise performance through effective management of negative impact factors that affect hider its successful operation. The paper provides the analysis of a range of external factors that can damage the enterprise economy along with suggesting the structuring of external factors of competitiveness with regard to each stage of the enterprise business plan implementation. The functional objectives of the enterprise economic security and specifics of shaping the economic security diagnostics system are discussed. The study also offers the review on the methods used to diagnose the environment effects on the enterprise competitive position in the context of its economic security. It is argued that the most significant indicators estimated by a number of selected criteria (structural elements) of a business competitive position within the system for enterprise economic security diagnostics are the following: the level of security by the financial component, the level of security by personnel component, the level of security by innovation and technology component, the level of security by political and legal component, the level of security by analytical information component and the level of security by economic component. The paper also suggests the methods and tools for business economic security diagnostics and explores the key objectives of the enterprise economic security management system.