采用基于第一性原理的密度泛函理论赝势平面波方法,对CrSi2的能带结构、态密度和光学性质进行了理论计算,能带结构计算表明CrSi2属于一种间接带隙半导体,禁带宽度为0.353eV;其能态密度主要由Cr的3d层电子和Si的3p层电子的能态密度决定;同时也计算了CrSi2的介电函数、反射率、折射率及吸收系数等.经比较,计算结果与已有的实验数据符合较好. The band structure, density of states and optical properties of CrSi2 are theoretically calculated by first-principles density functional theory (PFT) pseudopotential plane wave method. Band structure calculations show that CrSi2 belongs to an indirect band gap semiconductor. The band gap Is 0.353eV.The energy density is mainly determined by the energy density of the 3d layer of Cr and the 3p layer of Si.At the same time, the dielectric function, reflectivity, refractive index and absorption coefficient of CrSi2 are also calculated.By comparison, The calculated results are in good agreement with the existing experimental data.