用微扰理论和多层分割法求得到金属包层非均匀介质波导导模的传播常数的一级和二级近似解 ,与用复本征方程求得的精确解进行比较 ,给出了与精确值符合相当好的数值结果 ,结果表明微扰法是相当好的近似方法 ,二级近似结果对一级近似结果的修正很小 ,一级近似已可以给出足够精确的结果。 The perturbation theory and multi-layer segmentation method are used to obtain the first-order and second-order approximate solutions of the propagation constants of the cladding waveguide inhomogeneous medium. Compared with the exact solution obtained by the complex exponential equation, The exact values ​​are in good agreement with the numerical results. The results show that the perturbation method is a fairly good approximation. The second-order approximation results in small corrections to the first-order approximation results. The first-order approximation can give sufficiently accurate results.