Abstract: The existing analytical or semi-analytical methods cannot rigorously capture the geometrical effects of noncylindrical piles in elasto-plastic soils. To solve this issue, based on the principle of virtual work, the governing equations for the pile-soil system are derived. Solving the governing equation with a complex boundary is overcome by the conformal mapping technique. A semi-analytical algorithm for the vertically loaded noncylindrical piles in elasto-plastic soils is developed by combing the use of integral algorithm for the hyperbolic D-P constitutive model. A general theoretical model for the load transfer of the vertically loaded noncylindrical piles considering the geometrical effects is proposed. The reliability and efficiency of the proposed semi-analytical method is validated by comparing the predicted results with those of FEM. Finally, detailed parametric studies are conducted to investigate the geometrical effects on the influences of load-settlement curve. It is found that the non-circular cross-section has insignificant influences on the settlement of the pile head under working loads, which principally affects the magnitude of the ultimate bearing capacity of the pile.