World economy situation has undergone great changes since the 21st century. Chinese economy develops at a high speed. International influence grows with each passing day. Domestic large-scale enterprises, such as China National Petroleum Corporation (CNPC), launch a strategy of "walking out" positively, carry out overseas investment and acquisition, realize international operation and reinforce strategic cooperation internationally.With the stable growth of Chinese economy, China has an increasing demand for oil gas energy. In order to safeguard stable energy supplies required by domestic economic growth, and also realize corporate long-term development, China National Petroleum Corporation, constantly,conducts large-scale overseas merger and acquisition activities. In the process of overseas investment and acquisition, China National Petroleum Corporation will be faced with various complicated, changeable and unmanageable risk factors, such as political risk, economic risk, cultural risk and technical risk. Enterprises need to adopt scientific and effective risks prevention and countermeasures to identify risks, eliminate risk factors and reduce occurrence probabilities of risk events for ensuring success of overseas acquisition projects. This is good for long-term development of enterprises.This paper, based on China National Petroleum Corporation studies risk of overseas acquisition and merger risk, and analyzes advantages and disadvantages of implementing overseas mergers and acquisitions for China National Petroleum Corporation and opportunities and threats of external environment.This paper is based on part of overseas mergers and acquisitions and direct investment theory, and adopts PEST analytic method and SWOT analytic method to study and analyze confronting risk factors of overseas mergers and acquisitions for China National Petroleum Corporation (CNPC). By combining with conclusion of risk analysis, advantages, disadvantages, internal and external surroundings of CNPC, this paper proposes several recommendations on risk prevention and countermeasures of overseas acquisition and merger risk and provides certain actual reference significance on realizing scientificly strategic management in overseas, preventing acquisition and merger risk effectively and smoothly implementing overseas strategy for enterprises.