Abstract: The main pier of in Hezhang Bridge Guizhou province has a height of 195 m, which is supported by 20 rock-socketed piles with 2.5 m in diameter and 40 m in length. The engineering geological condition of the main pier site is very complex. In order to investigate its mechanical characteristics, end bearing and shaft resistance distribution, 3D finite element analyses for individual pile and pile group are carried out. Some valuable conclusions are drawn: the overlaying stratum shares a certain proportion of the upper load, so it is uneconomical to neglect its influence in design; the shaft resistance and tip resistance are not mobilized synchronously, the shaft resistance is mobilized prior to the tip resistance; the reasonable depth of rock-socketed piles can improve the shaft resistance and enhance the load sharing ratio of the tip resistance and the shaft resistance of the overlaying stratum.