The first step in the preparation of rare earth doped silica fiber is the preparation of the preform. The preform consists of rare-earth doped core glass rod and silica cladding. The preform is then heated and softened in a high-temperature furnace, and drawn into a fiber of a certain diameter under the action of traction, a process known as fiber drawing completed by drawing tower. In order to ensure the quality of the fiber material, appropriate detection methods and analysis methods must be selected to characterize the prepared fiber. This chapter will elaborate on the preparation of rare earth doped silica fiber preforms by chemical vapor deposition, non-chemical vapor deposition, and the drawing and characterization of rare earth doped silica fiber.