应用等效介质理论 ,提出了一种理论分析光子晶体的新平面波展开法 ,通过计算光子晶体的能带作收敛性分析 ,结果表明 ,新方法具有精度高、收敛快的优点 ,明显优于目前通用的二种平面波展开法 ;与已有的理论方法相比 ,新平面波展开法更适用于分析任意介电分布的高维光子晶体结构 Based on the theory of equivalent medium, a new theory of plane wave expansion of photonic crystals is proposed. By analyzing the energy band of photonic crystals, the results show that the new method has the advantages of high precision and fast convergence, which is obviously better than the current Generalized two kinds of plane wave expansion method; Compared with the existing theoretical methods, the new plane wave expansion method is more suitable for the analysis of any dielectric distribution of high-dimensional photonic crystal structure