Abstract: To fabricate high quality hollow glass microspheres (HGMs) by sol-gel technology for inertial confinement fusion (ICF), the effects of furnace atmosphere pressure on the transformation process from gel particles to HGMs and the resulting quality of HGMs were investigated by numerical simulation and experiments. The results show that decreasing of furnace atmosphere pressure can increase diameter of HGMs and decrease wall thickness of HGMs. Decreasing furnace atmosphere pressure can extend the refining time of liquid HGMs, however， the heat transfer coefficient between liquid and furnace atmosphere pressure decreases significantly with the decreasing of furnace atmosphere pressure. As a result, the refining degree and the quality of HGMs descend quickly with furnace atmosphere pressure. When the furnace atmosphere pressure is lower than 0.5×10⁵ Pa, the sphericity, concentricity and surface finish can not satisfy the restrict requirements of ICF targets.