As an improvement form of deep foundation, belled steel’s engineering research and application has matured. On the basis of belled steel pile, a new form of steel piles, explosive expansion steel piles, is proposed. Based on ABAQUS, the two-dimensional axisymmetric finite element contact model of pile and soil is set up. The parameters include: the diameter of the expanding section and highness of the expanding section have been analyzed through the Q-S curve. The results show that: the vertical bearing capacity increases significantly with the increase of the diameter of the expanding section, but decreases with the increase of the highness of the expanding section