Abstract: The physical process of liquid droplet method to fabricate hollow glass microspheres(HGM) is divided into 3 main sections as droplet formation, the formation and drying of gel shells, and the fusion of dried gel shells, to analyze the principles of HGM formation process and the influences of factors. As results, methods to quantitatively control the size and velocity of droplets and the amount of glass forming oxides in a single droplet are derived. And the effects of temperature profile, rate of purge gas and its components on the formation of HGM are discussed.