In order to facilitate the application of the screw pile in civil engineering, this paper deduces the expressions of the cross-sectional area and perimeter of the screw pile, and establishes the numerical calculation methods of the inertia moment based on four key sectional parameters (inside radius, screw pitch, height and thickness of thread). Then, the section geometric characteristics of the screw pile influenced by sectional parameters are discussed and compared with those of the circular pile within the scope of the size in engineering application. The results show that the screw pile cross-sectional area and perimeter increase with the increase of inside radius, height and thickness of the screw thread, but decrease with the increase of screw pitch. What's more, area increases more significantly than perimeter. The inside radius plays the most important part in influencing the cross-sectional area and perimeter. When the inside radius varies from 0.2 m to 0.5 m, the area increases 4.4 times and the perimeter increases 1.3 times. The perimeter ratio between the screw pile and the circular pile with the same sectional area is 1.00 to 1.05, and the area ratio between the screw pile and the circular pile with the same sectional perimeter is 0.91 to 0.99. Therefore, the perimeter of screw pile is only 0% to 5% larger than that of the circular pile with the same pile length and the same amount of concrete. The screw section has two main inertia moments:I_xc relative to symmetry axis of section and I_yc relative to axis perpendicular to symmetry axis and intersects with centroid of section, and I_xc is 13% to 72% larger than I_yc. They increase exponentially with inside radius, increase in contradictory trend with thickness of the screw thread, increase linearly with height of the screw thread, and decrease linearly with screw pitch. Compared with circular piles, the main inertia moment I_yc is smaller, while the other one I_xc is larger. However, compared with the circular pile with the same perimeter, the main inertia moment I_xc is smaller when thread thickness is less than 0.06m.