提出一种二维磁性光子晶体缺陷结构，实现了三端口Y形铁氧体柱环行器。采用平面波展开法和有限元方法计算环行器外部特性，计算结果表明：三角晶格二维光子晶体点缺陷微腔谐振频率与相应实验结果一致。在中心频率处，环行器传输效率最高，在输出与输入端口之间几乎没有能量损失;隔离度与插入损耗分别达到23.2 dB和0.003 7 dB。当偏离中心频率时，传输效率逐渐降低，随频率偏移量增大，环行器传输特性急剧变差。由于所设计的环行器以空气为背景，可克服空气孔结构Y形环行器隔离度低的不足，解决多个铁氧体柱带来的损耗大的问题，因此具有一定意义.

A new defect structure of twodimensional magnetic-photonic crystal was proposed and applied to implement the threeport Yjunction circulator using a ferrite cylinder. External characteristics of the circulator were calculated by the plane wave expansion method and finite element method, the numerical results show that there is an agreement between the resonance frequency of microcavity constructed by a point defect in the 2D triangular lattice photonic crystal with those results of corresponding experiments. In the center frequency, the transmission efficiency of the circulator is the highest and there is no energy loss between output port and input port; the isolation and insertion loss of circulator respectively reach 23.2 dB and 0.003 7 dB. When frequency diverges from the center frequency, the transmission efficiency gradually decreases with increasing frequency offset, and the transmission characteristics of the circulator sharply deteriorated. This design of circulator with air as background, can overcome low isolation of circulator with an array of air holes, and solve the high loss from multiple ferrite cylinders, having obvious superiorities.