Large Internet platform has strong network effect，extreme scale economy and important linkage function. It constructs a two-sided market system which is significantly different from the traditional market model. The market competition，monopoly behavior and regulatory governance of large Internet platforms cannot be simply defined by traditional industrial organization standards such as market structure，market behavior and market influence. The specific market competition，asymmetric pricing，cross-border network effect，and extreme scale economy make it difficult to use universal regulatory framework against platform monopoly，data monopoly and regulatory challenges. The potential consumer discrimination，data abuse，innovation barriers and systemic risks of large Internet platforms need to be analyzed from the new dimensions of bilateral or multilateral markets，from the economic domain to the social domain，and from Pareto optimization to the public choice policy. The definition of the systematic importance of large Internet platforms，the identification of platform monopoly including data monopoly，the matching of personalized platform and differentiated supervision，the data sovereignty and jurisdiction of cross-border platforms，and the expansion from economic supervision to social governance all pose great challenges to the regulatory authorities. Comprehensive supervision and effective governance of large Internet platform is urgent and important，and it is a long way to go to build a long-term supervision and governance mechanism that includes platform innovation，effectively deals with systemic risks，innovatively regulates platform monopoly and data abuse，properly handles digital sovereignty and effectively protects consumers.