Light scattering properties of textile fibers are essential in microscopic structure, optical properties and non-destructive examination for textile material. A published spectral approach is improved by utilizing anisotropic structural characteristics of textile fibers. The scattered electric fields of the oblique plane wave illuminating textile fibers and the Mueller matrix characterizing the scattering events are obtained, sequentially. Monte Carlo algorithm is then applied to simulate the multiple scattering of polarized light illuminating obliquely the parallel cotton fiber assemblies, and its results are verified experimentally. The scattering pattern calculated theoretically is in good agreement with the one measured experimentally on shape features and intensity distribution, which indicates the validity of Monte Carlo method for simulating the textile fibers scattering in this paper and indicates that this method has important guiding significance in the theoretical study of light propagation characteristics of textile material.