For large-mode-area (LMA) fiber laser, the beam quality is not as good as that of single mode fiber laser. A tapered section was introduced to a LMA fiber. The core diameter of the smallest part was 9 μm, which was located 5 mm away from the output end of the fiber and about three times smaller than the conventional fiber core with the diameter of 26 μm. The experimental results show that the beam quality factor M2 is reduced from 3.50 to 1.81, with the slope efficiency from 63.6% to 51.1%. Although the tapering induces 19.8% power loss, the brightness of the tapered fiber laser is 3 times as much as that of the untapered.