A novel, simple, and low-cost in situ surface vitrification method has been effectively developed to enhance the optical transparency of rough surface sapphire at UV-visible-IR regions. This method is to obtain a glass layer on the sapphire surface through vitrifaction process. The thickness, refractive index, components and transition temperature of the glass layer have been investigated and discussed respectively by XRD, DSC, SEM and EDS elemental analysis. The experimental results show that the vitrified sapphire has high transparency even after 1000 °C annealing at UV-visible-IR regions.