Nowadays, with the rapid progress in information technology revolution, the Internet has penetrated into almost every field in human life, including political, economic, military and social aspects, and also has had a profound effect on its development. The network has been integrated into every aspect of human social life, greatly changed people's production way and lifestyle, and formed an interdependent international system. At the same time, the problem of network security is increasingly prominent. Especially after the Snowden incident, the global network security issues are on the agenda. Cybersecurity has become a part of national security strategy, and it has affected the development of Sino-U.S. relations. As thus, it should be urgently resolved. Cybersecurity can be analyzed from many different angles, and this thesis tries to analyze it using the international relations theory. There is no doubt that a network is a dominant factor of production. Compared to capital, labor and other factors of production, it has more critical effects on economic development. Its flow will inevitably affect the international systems, the relationship between the state and national internal structure, and the corresponding political process. Also, cybersecurity is to ensure network security, so it is viable to analyze cybersecurity from the aspect of international relations. To analyze Sino-U.S. cybersecurity, this thesis first defines cybersecurity and threats to cybersecurity, and then combines Sino-U.S. relations, in order to basically understand how cybersecurity affects Sino-U.S. relations in recent years. Why it suddenly becomes an obstacle to the relations? To find out the answer, the international relations theory and the interdependence theory are used to analyze the cybersecurity problems in the U.S. and China. The U.S. is the world’s most developed country, while China is a developing country. They both face cybersecurity threats from each other or from other countries, and the two countries have different security strategies. Facing the asymmetric cybersecurity environment, both of the U.S. and China are so anxious since it affects their dominant position in the next round of information technology in the future. Hence, the U.S. and China have to work out some mechanisms for enhancing cooperation on cybersecurity.