Abstract: Internet platform responsibility is the legal conscription and regulation of the gatekeeping power of platform to achieve certain internet regulatory aims. There are three stages of the development of internet platform responsibility theory and practice. Theoretically, it can be understood in the frameworks of institutional "gatekeeper", Technical "gatekeeper" and algorithmic "gatekeeper", which respectively correspond to the regulatory tolerance of internet platforms, the increasing pressure for more content gatekeeping obligation of platform beyond "safe harbor" and its controversy, and the direct regulation of the gatekeeping power of platform in context of ubiquitous computing. The new Chinese "E-Commerce Law" of 2018 represents the function expansion of platform responsibility regime from indirect tort liability to accountability, from behavior control to technology regulation. All in all, internet platform responsibility regime in the future should include the gatekeeping obligation of platform for hosted content as well as the regulation of the technical and business operation of platforms. It is essential to further study an implementing approach of platform responsibility which can reach balance of multiple interests, and the compatibility with market incentives.