China’s straight baseline regime deviates from the UN Convention on the Law of the Sea in a number of ways. Such discrepancies are likely to induce legal and political conflicts between countries, and also the settlement of which would not be easy, in particular, among the East Asian countries. In consideration of this point, the legal issues surrounding China’s straight baselines and basepoints should be analyzed and evaluated not only from the perspectives of UNCLOS, but also through comparative analyses based on customary international law, State practices, and special circumstances. Many of China’s State practices and laws based on straight baselines are neither in accordance with international laws, nor generally recognized as being in accordance with the international law of the sea. This paper provides important legal insights into China’s straight baselines, which are unlawful from the perspectives of UNCLOS and State practices, and, in addition, suggest desirable ways to solve the problems in international laws.