The utility model discloses a liquefied natural gas's gas supply system, including the gas cylinder, fix the guard circle of gas cylinder bottleneck end and be used for with liquid in the gas cylinder converts gaseous vaporization assembly into, the wallboard of guard circle is followed the outer wall of gas cylinder department upwards extend with form by the accommodation space that the wallboard encloses, the vaporization assembly is located in the accommodation space, the vaporization assembly include with liquid convert into gaseous heat exchanger with be used for keeping in through the buffer tank of the gas that the heat exchanger obtained after changeing, the heat exchanger pass through liquid outlet pipe with the liquid outlet of gas cylinder links to each other. The utility model discloses a gas supply system has increased the ground clearance of vaporization assembly to the assembly setting of will vaporizing is protected in the guard circle, avoids exposing outside, reduced with the interference in the external world, also reduced the risk of breaking and leaking simultaneously.