提出一种新的二维磁性光子晶体缺陷结构，并采用该结构使用5个铁氧体柱实现了四端口十字型铁氧体柱环行器。在得到的正方晶格二维光子晶体点缺陷微腔谐振频率与文献中相应的数值结果一致的基础上，采用平面波展开法和有限元方法计算环行器的外部特性。数值结果表明：在中心频率处，环行器隔离度最高达23.49 dB，插入损耗最低为0.0281 dB；当偏离中心频率时，随着偏移量的增大，环行器的传输性能逐渐变差。设计的环行器的波导内只有一个柱体，从而解决了已有结构中多个柱体带来的插入损耗大的问题。

A new defect structure of two-dimensional magnetic-photonic crystal with dielectric cylinders is given and a four-port cross-shaped circulator using five ferrite posts is envisaged. Based on the agreements between the resonance frequency of micro-cavity constructed by a point defect in the two-dimensional (2D) square lattice photonic crystal with those numerical results of related literatures, external characteristics of the circulator are calculated by the plane wave expansion method and finite element method. The results show that at the center frequency, the isolation of circulator is up to 23.49dB and the lowest insertion loss is 0.0281 dB; when frequency diverges from the center frequency, the transmission characteristics of the circulator deteriorate gradually with increasing frequency offset. This design of circulator with only one ferrite cylinder in the waveguides, which solves the high loss from multiple cylinders.