基于第一性原理赝势平面波方法，对稀土(Y、Ce)掺杂β-FeSi2的几何结构、电子结构和光学性质进行了计算与分析。几何结构的计算表明，Y 或Ce掺杂后β-FeSi2的晶格常数改变，晶胞体积减小。电子结构的计算表明，掺入稀土后β-FeSi2 费米面附近的能带结构变得复杂，带隙变窄；总电子态密度发生了变化，Y 的4d 轨道电子态密度和Ce的4f轨道电子态密度主要贡献给费米面附近。光学性质的计算结果表明，Y 或Ce 掺杂后β-FeSi2 的静态介电常数明显提高，介电函数虚部ε2 的峰值均向低能方向移动并且减弱，折射率n0 明显提高，消光系数k 的峰值减弱，计算结果为β-FeSi2材料掺杂稀土改性的实验研究提供了理论依据。

By using the first principle pseudo-potential plane-wave method, the geometrical structure, electronic structure and optical properties of β-FeSi2 with doping rare earth (Y、Ce) are calculated and analyzed. The calculated results of the geometrical structure show that the lattice constants change, the volume of lattice reduces. Electronic structure calculation indicates that band structure near the gap becomes complex, and bandgap becomes narrow obviously. The total density of state changes, and the density of states for Y-4d and Ce-4f are mainly contributing to the Fermi energy level. Optical properties calculation indicates that the static dielectric constant increases, the peak of the imaginary part of dielectric function ε2 decreases and moves to a lower energy, the refractive index n0 increases significantly and the peak of k decreases. These results offer theoretical data for experimental study β-FeSi2 doped with rare earth modification.