Recently, most impermeability seudies of polypropylene fiber concrete, as a new sort of tunnel lining waterproof material,are limited to the impervious mechanism and unable to be satisfied with the engineering need. On the basis of fracture mechanics and the micro structure mechanics, the resistance of fiber to the crack extension inside concrete and it’s SIF were deduced, the analytical formula of fiber resistance effect to the opening mode crack extension was presented as well. Meanwhile, the impervious performance of polypropylene fiber concrete was explained reasonably by the numerical calculation of the resistance effect. On the other hand, for comparing the impervious performance of polypropylene fiber concrete with that of UEA concrete, the impervious performance experiments of four groups of different types of concrete were carried out, it is presented that the former is superior to the latter. More than that, adding double polypropylene fiber and UEA to the concrete with proper proportion will make the impervious performance much better.