In order to further improve the multimode fiber transmission performance in the Ethernet, the paper proposes to improve the performance of wide-band bending insensitive multimode fiber considering the material composition and profile structure design. By optimizing the concentration distribution of the doped elements in the core, the sensitivity between the parameter of optimal profile refractive index distribution αopt and the wavelength is reduced, and the fiber bandwidth characteristics is improved. In addition, the new design contains an inner cladding which can adjust the profile structure continuously at the interface of core and cladding. The continuous adjustable structure can reduce the influence of viscosity difference between the core layer and the trench on the fiber performance. It can also alter the delay of higher-order modes very effectively to eliminate the impact of trench structure on fiber bandwidth characteristics, by adjusting inner cladding profile. The results show that the fiber with the new structure has not only higher bandwidth characteristics, but also lower bending loss.