Disclosed is a method for fabricating high-purity silica glass using a sol-gel processing that includes the steps of: (a) mixing deionized water with a monomer and a dimer to prepare an aqueous premix solution; (b) mixing the aqueous premix solution with a fused silica and a dispersion agent; (c) mixing the resulting mixture to form a dispersed sol; (d) aging the dispersed sol at the ambient temperature to stabilize silica particles, and removing air voids from the sol; and, (e) adding a polymerization initiator and a gelation agent to the aged sol.