According to the geometry characteristics of tapered pile cap, differential deformation of pile-soil and soil arching effect in embankment, the pile-soil stress ratio calculation formula for the composite foundation with tapered pile cap was deduced, taking into account the behavior of pile top piercing the embankment and pile end punching the soft substratum. Numerical model was established by using finite difference software（FLAC3D）. The numerical results of the pile-soil stress ratio decrease from 3.06 to 2.08 as the taper angle increases from 5.7° to 14°, and the calculated results decrease from 3.13 to 2.19 accordingly. The relative error falls within the range of 2.01%~6.44%，which indicates that the calculated value of pile-soil stress ratio is consistent with the simulation value. Furthermore，the effects of equal section piles，conventional pile with cap and taper-capped pile on the settlement of embankment were compared. With the same size of the top section of the pile，the composite foundation with tapered pile cap exhibits a smaller settlement value.