An apparatus of charging Liquefied Petroleum Gas (LPG) fuel of a bi-fuel vehicle includes: a gasoline mixing chamber mounted on an LPG bombe side, a gasoline fuel supply line connecting the gasoline mixing chamber with a fuel tank and allowing gasoline fuel to move to the gasoline mixing chamber as a first valve is open, an LPG fuel supply line connecting an LPG bombe with the gasoline mixing chamber and allowing LPG fuel to move to the gasoline mixing chamber as a second valve is open, and a control unit configured to open the first valve and control the LPG fuel to be recirculated to the LPG bombe together with the gasoline fuel by a pressure of the LPG fuel moving to the gasoline mixing chamber, as an internal pressure of the LPG bombe reaches a predetermined reference pressure.