The studies of silica nanoclusters are of substantial interest for large potential in applications as diverse as photonics/optics, microelectronics and catalysis. In this study, we used the basing-hopping method with Buckingham potential to get the stable structures of silica nanoclusters ((SiO2)(n) = 1-13). The global minimum geometry of silica nanoclusters were determined by density functional theory calculation. We investigated the energy gap, binding energy and second order energy difference of nanoclusters to determine their structural stability with different sizes. We also calculate the second-order energy difference, binding energy to determine the magic number.