This chapter explores the problems and tasks of New China in the ocean legal system. It first analyzes the development stages and trends of the UNCLOS system, providing a foundational understanding of the international legal framework. Then, it examines China’s specific legislative practice in accordance with international ocean rules, including the relationship between international law and domestic law, and China’s concrete efforts in the modern law of the sea system. Subsequently, the paper addresses the practical problems of China’s ocean legal system, focusing on practical challenges and corresponding domestic improvement measures. Finally, it delves into the institutional challenges regarding innocent passage in territorial waters and China’s response, covering questions raised, the purpose of the right and its relationship with other regimes, legal elements and restrictions on warships, as well as the illegality of unauthorized entry of U.S.warships into China’s Xisha Qundao territorial waters and China’s response strategy.