Relationship between boron-doped content and single polarization single mode band-width of W-tunneling optical fiber is analysed. The band-width is independent on the boron-doped content and is determined only by the profile structure and refractive index depth of the inner cladding when the fiber is long enough. For short W-tunneling optical fiber, increasing of boron doped content can raise leakage losses of the fundamental modes below cut-off. It can enhance extinction ratio and effective band-width of the fiber to some extent.