Fiber is the complex system consisting of diverse microscopic structures with the complicated changing law. The formation of artificial fibers is the multi-component, nonequilibrium and nonlinear process. While only static structure information of fibers can be obtained by using the traditional X-ray measurement technique. In order to take a deep look into the formation and evolution process of materials' structure during the processing and using procedure, a novel research method with high time and space resolution should be established. In situ X-ray measurement technique has received wide attention and developed rapidly since it was brought forth firstly. Compared with the traditional X-ray measurement technique, in situ measurement can detect the process of structure's formation and evolution in a more direct and precise way. Because of the outstanding characteristics of high brightness, high collimation degree of synchrotron radiation, the advantages like high time resolution and high space resolution of in situ X-ray measurement by using synchrotron radiation can be fully exploited to reveal the dynamic evolution process and microscopic scale structures of materials. In this review, combined with the domestic and international researchers' specific works, the research about in situ X-ray measurement of fibers with the application of synchrotron radiation was introduced, including the process of fibers' formation and drawing of post-treatment.

Contents
1 Introduction
2 In situ studies on process of fiber formation
2.1 In situ studies on melt-spinning process of fibers
2.2 In situ studies on other methods of spinning process
3 In situ studies on post-treatment process and stretching process of fibers
3.1 High performance fibers
3.2 Conventional fibers
3.3 Natural fibers
4 In situ studies on other aspects
5 Conclusions