Laser beam shaping is an important subject for industrial and medical applications since different applications may require different laser intensity distributions. We present an all-fiber beam-shaping device that could transform a Gaussian-shaped laser beam into an intensity uniform beam in the $1.0\mathrm{\mu m}$ wavelength region using a long-period grating (LPG). The device can be used to shape the beam of a Yb-doped high-power fiber laser. The mode structure of the LPGs made of HI1060 fiber is analyzed. The design parameters that affect the beam shaping are discussed, and the results of the beam shaping using two cladding modes, ${\mathrm{LP}}_{03}$ and ${\mathrm{LP}}_{04}$ , are presented.