A method of controlling fuel injection of a bi-fuel vehicle running on gasoline and liquefied petroleum gas (LPG), and more particularly, a method of controlling fuel injection of a bi-fuel vehicle having an engine running on gasoline and LPG, capable of simultaneously controlling supply systems and injectors of fuels and switching the fuels in response to a fuel switch request based on an injection ratio and an injection time of each fuel is provided. Thus, fuels may be switched stably and efficiently, output reduction and exhaust gas increase due to deviation of an air-fuel ratio while switching fuels may be prevented, and fuels may be appropriately switched. Furthermore, mechanical stress generated while switching fuels may be minimized and stable driving may be provided. Accordingly, the reliability of a bi-fuel vehicle simultaneously using gasoline and LPG may be improved and the competitiveness of bi-fuel vehicle products may also be improved.