Abstract: On the basis of beam large deformation theory, the paper promotes the large deformation numerical modeling of homogenous muti-layers folding process and results. The results show that the fold is symmetrical when the boundary of two-side pushing is symmetrical; the fold is non-symmetrical when it is non-symmetrical. It brings to light the mechanical reason of folds. The results also show that large deformation mechanics theory has a bright future in the modeling research of tectonics.