环形器是微波系统中一种常用的元件，能够选择出射端口定向传播微波.由于微波元件不同于低频的集中参数元件，学生不易形成清晰的物理图像.本文运用COMSOL软件建立了铁氧体环形器模型，使用散射矩阵元（S参数）定量地研究了几何参数对于环形器定向导波性能的影响，并确定了性能较优时对应的几何参数；通过电场分布图和能流流向图直观地展现了微波在环形器中的传播行为.对学生建立环形器定向传输微波的物理图像很有帮助． 

The circulator is a commonly used element in the microwave system, which is capable of selecting the directional propagation of microwaves. Since the microwave element is different from a low frequency centralized parameter element, the students are not easy to form a clear physical image. In this paper, the model of ferrite circulator is established by using COMSOL software. The influence of geometric parameters on the directional guided wave performance of circulator is quantitatively studied by using scattering matrix element (S parameter), and the corresponding geometric parameters when the performance is better are determined; The propagation behavior of microwave in the circulator is intuitively displayed by electric field distribution diagram and energy flow direction diagram. It is very helpful for students to establish the physical image of directional transmission of microwave by circulator.