The invention discloses a quartz rod structure for changing a refractive index profile by an external exposure method, and relates to the field of optical fiber amplifiers and optical fiber lasers. The quartz rod structure comprises an exposure area (1) and an active quartz rod, wherein the active quartz rod comprises an active quartz rod core (2) and an externally wrapping layer (3); the exposure area is formed in the active quartz rod core and is subjected to external exposure from the end of the active quartz rod core, and exposure light beams change the refractive index of the exposure area; and the refractive index of the exposure area, the refractive index of the active quartz rod and the refractive index of the externally wrapping layer are gradually decreased in turn, wherein the refractive index range of the exposure area is between 1.455 and 1.459, the refractive index range of the active quartz rod is between 1.453 and 1.455, and the refractive index range of the externally wrapping layer is between 1.450 and 1.452. The quartz rod structure solves the problem that a high-power optical fiber laser or amplifier needs a high-quality quartz rod, and ensures that the quartz rods with different shapes and refractive index profiles are manufactured simply and feasibly.