Several kinds of important preparation processes of synthetic optical silica glass are elaborated, such as Chemical Vapor Deposition (CVD), Plasma Chemical Vapor Deposition (PCVD) and indirect synthetic method. The raw materials and characteristics for the optical silica glass, as well their applications in different fields are given. Then, developing situations and tendencies of these preparation processes are reviewed. It compares their advantages and shortcomings in detail. Among them, the CVD is the most mature and commercial technology. It prepares the synthetic silica glass with a diameter of 600 mm or beyond, its optical uniformity is better than 2×10-6, and the laser damage threshold is 30 J/cm2@355 nm. The PCVD processes synthetic silica glass of full-spectrum transmittance. It shows excellent internal quality, its hydroxyl content is less than 5×10-6, and the spectral transmittance of T190-4000 nm is more than 80%. Furthermore, the indirect synthetic method prepares the synthetic silica glass with an absorption coefficient less than 1×10-6/cm@1064 nm, its hydroxyl content is less than 1×10-6, and the spectral transmittance of T157-4000 nm is more than 80%. Moreover, the indirect synthetic method is beneficial to doping and controlling the defects of synthetic silica glass, which achieves all kinds of special functional silica glass. It suggests that each of these preparation processes of synthetic optical silica glass has its own advantages and disadvantages, so proper preparation processes could be adopted for different application requirements of modern high-end photoelectron technological fields.