Abstract: After breakdown of a liquefied natural gas bus, the cut-off valve of the gas cylinder was closed.And then the gas supply system experienced pipeline freezing and natural gas leakage.The buffer tank in the gas supply system exploded when the pipeline was deiced with normal temperature natural water.The explosion reason for the buffer tank was analyzed by chemical composition test, microstructure and fracture morphology observation, and stress checking.The results show that the liquefied natural gas experienced rapid phase transition during the deicing with normal temperature water, leading to sharply increased pressure in the system.When the pressure exceeded the explosion pressure of the buffer tank, the buffer tank exploded.It was suggested to install a secondary safety valve on the top of the buffer tank, and to set a vent pipe for the safety valve.The risk of explosion of the buffer tank could be effectively reduced by venting the pressure through the vent pipe.