Aiming at the effect of piles-soil interaction on high pier stability, this paper, based on the equal force- effect principle, substituted pile foundation to a "pier-style + level spring" mode to simulate that effect, then a critical load calculation method considering the pier- piles-soil system under the vertical load was developed. And to validate the method proposed, an engineering example was illustrated. The calculation results have shown that this method is reasonable. Finally, based on the example and formula, the effect of pier stiffness and height changes on the system stability was analyzed, and the results have shown that the pier stiffness and height are two important performances to the system. Structure buckling is not a material damage problem, but has an optimal stiffness and length ratio in high pier and pile foundation system, which makes every part of the structure work in coordination.