The co-volatilization of boron and silicon has been studied for determination of SiO2 content in boron-containing silica refractories. The co-volatilization of boron may cause positive interference for determining of SiO2 content. The interference can be eliminated by the volatilization of boron with 5mL and 2mL of ethanol by separately volatizing, before volatilization of SiO2 with hydrofluoric acid. The method for determination of SiO2 content in boron-containing silica refractories has been established. The scope and precision of this method are equaled to that of the conventional method by hydrofluoric acid gravimetry.