With the increasing globalisation of the natural gas supply,supply interruptions,serious shortages and price hikes may affect or even damage many aspects of a country or region.Nowadays,natural gas has become one of China's main energy sources,and the safety,stability and sustainability of its supply are related to the energy security of our country.The main issues threatening the security of the natural gas supply are as follows: (1) high dependency on foreign countries;(2) weaknesses in domestic natural gas infrastructure;(3)the instability of the international common security system.In the fourth part,from the perspective of both internal and external security,the following countermeasures for strengthening our natural gas supply security system are put forward: (4)accelerate the upgrading of domestic natural gas supply-side capacity and enhance domestic gas supply security;(5)promote the construction of domestic natural gas infrastructure in order to break the bottleneck in domestic gas storage and transportation;(6)promote the capacity building of emergency peak shaving on the domestic natural gas demand side so as to enhance the stable demand-side supply;and 7 deepen energy cooperation in Belt and Road regions in order to plot a "fishbone diagram of the safe supply of natural gas in China" for the stability of the external supply.