Institutional opening-up， with institutional arrangements concerning rules， regulations， management and standards as its primary focus， is an essential requirement for advancing China’s high-level opening-up. Since the Third Plenary Session of the 18th Central Committee of the Communist Party of China， China has continued to explore ways of advancing institutional opening-up through the development of pilot free trade zones and the Hainan Free Trade Port， as well as through Belt and Road cooperation. Against the backdrop of intensifying competition over international economic and trade rules， how institutional opening-up can provide greater certainty for high-quality development has become an important issue requiring urgent attention. This paper traces the evolutionary trajectory of institutional opening-up across three dimensions—policy evolution， practical exploration， and scholarly research. It then examines four key issues： its significance， guiding principles， priorities， and approaches to implementation. Furthermore， by analyzing five sets of relationships—between opening-up based primarily on flows of goods and factors and institutional opening-up， between at-the-border and behind-the-border opening-up， between domestic market integration and external opening-up， between institutional innovation and institutional opening-up， and between opening-up in trade in goods and trade in services—the paper clarifies the conceptual boundaries of institutional opening-up and the connections among these concepts， thereby providing theoretical insights and practical implications for its steady advancement.