Variable charge molecular dynamics simulations of vitreous silica have been performed based on the iterative fluctuation charge model. The vitreous silica was formed using the standard melt-quench process. The pair distribution function, angle distribution and frequency spectrum were then obtained. The results are in good agreement with experimental data. More importantly, our results show that the atomic charge in vitreous silica is significantly different from those in the crystalline silica, and larger fluctuations are observed.