给出了W型单模单偏振光纤基模模场在截止前、截止时和截止后的具体计算方法。利用基模模场分析了W型单模单偏振光纤隧道效应发生的过程、强弱和方向 ,得出了W型单模单偏振光纤隧道效应随其基模的截止而显著增强、并且主要集中在椭圆内包层短半轴方向的结论。 The calculation method of the mode field of the W-mode single-mode single-polarization single-mode optical fiber before cut-off, cut-off and cut-off is given. Based on the fundamental mode field, the tunneling effect, the strength and the direction of the W-mode single-mode single-polarization optical fiber are analyzed. The tunneling effect of the W-mode single mode single polarization fiber is obviously enhanced with the cut- Conclusion in the direction of the shorter axis of the inner cladding of the ellipse.