Abstract: The Air Defence Identification Zones (ADIZ) is controversial because of its “grey area” in international law, and the international community has neither explicitly opposed nor explicitly supported the legality of the ADIZ. China established the East China Sea ADIZ in 2013. Disputes mainly stem from whether it may constitute de facto sovereignty over the disputed waters, thereby hindering the freedom of overflight and navigation, and whether it may break through the restricted jurisdiction of information collection and turn it into a militarized area. In fact, the ADIZ is a derivative of the contradiction between maritime rights and freedom of navigation in the international law of the sea. The international community's tolerance for the ADIZ comes from the fact that the establishment of the ADIZ by coastal states mostly abides by some existing consensus. International hedging theory can explain why ADIZ still exist and are valued in a contemporary world where the significance of national defense security is diminished. ADIZ is an effective tool for coastal states to safeguard maritime interests, but it may also complicate the disputed waters, which depends on the rational attitude and prudent behavior of various stakeholders.