Polylactic fiber is a new renewable and biodegradable polymer material for its better physical property and thermoplastic and biological properties, while there are no corresponding inspection method to characterize and identify polylactic fiber with other fibers. So, the present paper is to qualitative analyze the features of PLA fiber and identify it with general fibers, including Polyester, Polyamide, Polyacrylic, Diacetate, Cotton, Viscose and Silk fibers. Elementary analysis method is utilized to have the definite analysis of fiber purity degree and category by the corresoponding element contents of constructing elements. The experimental results show that there exist good accordance with the theoretical results, and is suitable for qualitative characterizaion and identification of fibers. Gas chromatography mass spectrum method is used to feature marker functional groups of these eight fibers, and to further have a qualitative analysis of each fiber. IR spectroscopy proves the qualitative identification on fiber category by the marker absorbing peaks of functional groups ranging from 650cm-1-2200cm-1. These results will be greatly helpful in the qualitative analysis and indectification of Polylactic fiber.