道床是轨道结构的重要组成部分，道床截面的几何形状通常是由设计规范确定的．设计规范中对道床截面几何形状规定的取值是根据经验或半经验制定的，缺乏理论依据．本文应用优化理论，借助有限元分析方法，并考虑道碴材料的非线性性质，建立了铁路道床形状优化分析模型．运用该模型，文章分析了不同机车、不同道碴材料、不同路基条件下的道床厚度及边坡比． The track bed is an important part of the track structure. The geometry of the track bed section is usually determined by the design specifications. Design specifications of the cross-section of the track geometry is based on the value of empirical or semi-empirical formulation, the lack of theoretical basis. In this paper, optimization theory of railroad track, shape optimization analysis model of railroad track is established by means of finite element analysis and considering the nonlinear properties of ballast material. By using this model, the paper analyzes the track bed thickness and slope ratio under different locomotives, different ballast materials and different subgrade conditions.