Abstract: Data monopoly and its impact on market competition is a difficult issue in antitrust analysis of digital platforms. Factors such as gatekeeper status, switching costs, artificial intelligence algorithms, and imperfect data protection systems intensify the control of data by digital platform companies, and promote the formation of highly centralized and even winners-eat-all market structure. Data monopoly can not only improve market efficiency through various channels, but also easily restrict and eliminate competition, depriving users and third-party manufacturers of the benefits. Data anti-monopoly supervision should fully consider the complex characteristics of data as both public and private products, and focus on issues such as data protection, sharing, transplantation, security, algorithms and use, restricting discriminatory behavior in the field of data, exploring the construction and development of data commons, and encouraging the formation of a relatively complete system in terms of data decentralized storage.