In order to study the torsional behavior of longitudinal special-shaped piles, a longitudinal cross-section pile torsion elasto-plastic analysis model was built in homogeneous soil ground. The model considers variable cross-section of the special-shaped pile, and the pile-soil system along the depth direction is divided into finite segments. Based on the T-φ curve at traditional circular pile top and the torque-angle distribution curves along the pile shaft, the corresponding formula was obtained. The calculation program was run through MATLAB software. The torsional behaviors of longitudinal special-shaped piles and uniform circular piles were comparatively analyzed. The optimum design parameters for tapered pile were analyzed. The results show that the torsional performance is influenced by the top pile diameter obviously. The torsional performances of longitudinal cross-section special-shaped pile are relatively better than those of uniform circular pile with the same concrete usage. The torsional bearing capacity of tapered pile increases with the increase of the shear modulus, diameter, and taper angle, and the torsional bearing capacity is improved to 3~5 times under two times diameter.