Designed a two-dimension photonic crystal of square lattice with rotating square cylinders, calculated their frequency band structures for this kind of photonic crystal and found existing a large absolute band gap in the low and high frequency regions by using the plane wave expansion method. 设计了一种二维方形旋转正四边形直柱光子晶体,利用平面波展开方法计算了其光子频率带结构,发现在低频和高频区域,该类光子晶体的光子频率禁带明显增大。