文章介绍了光纤偏振模色散(PMD)的基本概念及影响因素。通过一系列试验分析了光纤包层不圆度与PMD的关系，指出为控制光纤PMD的稳定性，提高光纤在绕盘状态下测得的PMD值的可信度，需要将光纤包层不圆度控制在一个较小的范围内。利用光纤旋转技术则可以延展这一控制范围。

The fundamental concept of optical fiber PMD and the factors affecting PMD are introduced in this paper. On the basis of analyzing the relationship between the cladding noncircularity and PMD through a series of tests, it is indicated that in order to control the stability of fiber PMD and the reliability of the PMD values measured when the fiber is rewound on the bobbin, it is necessary to control the cladding noncircularity within a reasonably small range, which can be extended by the fiber spinning technology.