The core glass and cladding glass of gain guided index-antiguided (GGIAG) fiber doped with Yb3+ are prepared and Yb3+GGIAG fiber with core diameter of 120 μm, inner cladding diameter 220 μm and outer cladding diameter 260 μm is drawn by the rod-in tube technique. Yb3+GGIAG fiber has a lower core refractive index than the surrounding cladding′s, Δn=-0.00094. The beam quality factors in both horizontal and vertical directions are observed, M2x≈2.724 and M2y≈2.642 when signal light (at 1040 nm) with single mode is propagating in Yb3+GGIAG fiber with different length, which indicates single mode approximation behavior of Yb3+GGIAG fiber. The mode field diameter of Yb3+GGIAG is calculated to be more than 150 μm.