The invention provides an all-fiber Bessel light beam generator which is composed of a standard single-core fiber, an annular core fiber and a graded index fiber. When light wave is input to the single-core fiber, the transmission light wave can be coupled to the annular core fiber to form an annular light field, then the annular light field is formed into the Bessel light beam at a fiber end through the equivalent Fourier expansion optical transformation of the graded index fiber. Due to the light beam generator provided by the invention employing an all-fiber system, the graded index fiber is used for realizing a function of the lens, the whole generator is easy to align and is more stable compared with the traditional geometry optical system. In addition, the light beam generator has the characteristics of minimal structure, agile operation and strong anti-interference capability. The light beam generator can be applied to the fields of light beam generation, particle controlling and sensing and the like.