Abstract: Having shorter diameter and lower lateral bearing capacity, driven piles are usually used to carry vertical load and can be calculated as axial compressed member. The circle section is rather reasonable for axial compressed member. Because of their longer diameter and greater lateral bearing capacity, bored piles must be calculated as an eccentric compressed member carrying both of vertical and horizontal load. The mechanical ability of circle section is not better than rectangle section in an eccentric compressed member. In order to improve the structure of pile foundation and raise its bearing capacity it is needed to study and use the rectangle-section bored cast-in-situ piles, This article discusses its rationality and puts forward a construction method of rectangle-section bored piles.