An LPG bombe cooling system of a bi-fuel vehicle using both gasoline and LPG is provided. The LPG bombe cooling system is configured to cool the interior of an LPG bombe and to reduce the vapor pressure of LPG by supplying some gasoline from a gasoline tank into the LPG bombe using the fact that the temperature of gasoline in the gasoline tank is lower than the temperature of LPG in the LPG bombe, whereby it is possible to easily refill the LPG bombe with LPG even in the case in which the external temperature is very high, e.g. in the hot season.