Abstract: Based on the prototype tall pier bridge on Jingtai Highway, one new composite tall pier is designed. By utilizing the finite element software, the solid models are established for the nonlinear stability analysis of the tall pier under the cantilever stage, and the beam model for the pier after construction. Then, the stability capacity and coefficients were obtained. The parametric analysis was carried out to investigate the influence of thickness, of the yield point of LYP steel plate, of the height of specimens and, of the distance of a tie beam. Numerical calculations show that: unbalanced cantilever construction stage is the most unfavorable condition for the bridge, and the failure mode is compression-bending in longitude. The stability coefficient decreases by 30% compared with the balanced cantilever construction. Under different working conditions, the maximum strain of steel tubes occurred around 0.1~0.2 height of the CFST column on the compression side. With the increase of the slenderness ratio of the pier, the stability decreases significantly, and the failure mode gradually transforms from elastoplastic instability to elastic instability. The increase in the thickness of the LYP steel plate is beneficial to the improvement of the stability. It is favorable for the stability of the pier that the distance of tie beams is designed according to the experience of conventional tall piers, i.e. 10 m~12 m. Based on the parametric analysis, proposed are a new simplified model for new composite tall piers and formulas for calculating the stability capacity. The theoretical calculation results are in a good agreement with the numerical results when the slenderness ratio of the tall pier more than 70. When the slenderness ratio less than 70, it is accepted to calculate the stability capacity by the reduction of the bearing capacity of stocky columns.