The invention relates to a bend-insensitive multimode fiber comprising a core layer, inner sheath layers and an outer sheath layer. The bend-insensitive multimode fiber is characterized in that the radius R1 of the core layer is 23-26 micrometers, the refractivity section of the core layer is parabolic, the distribution index Alpha thereof is 1.9-2.2, a maximum relative refractive index difference Delta1 thereof is 0.9-1.2%, the first inner sheath layer, the second inner sheath layer and a recessed sheath layer are provided in order from inside to outside, the unilateral width of the first inner sheath layer is 1-3 micrometers, a relative refractive index difference Delta2 of the first inner sheath layer is -0.02-0.02%, the second inner sheath layer is an all-carbon dioxide layer 2-6 micrometers in unilateral width, the recessed sheath layer is an F-doped silica glass layer, and the recessed sheath layer is an all-silica glass layer. The double-inner-sheath structure of matching viscosity is used, the influence of drawing tension upon the core layer is reduced in terms of viscosity, and bend sensitiveness of the fiber is reduced; the width of the inner sheath layers and the size of the recessed sheath layer are reasonably optimized and designed, matching of the width and the size is achieved, and optimal width and size are acquired; meanwhile, excellent bend resistance and DMD (differential mode delay) performance are achieved.