Polyimide (PI) is a polymer having a rigid aromatic chain as a basic structure with excellent properties such as electrical insulation and low dielectric constant as well as excellent thermal and chemical properties, and is widely used in various industrial fields. In order to improve the characteristics of PI fibers, the thermal properties were analyzed and the effects on elongation rates were investigated. In this study, we used 4,4'-oxydianiline (ODA) and 2,2'-Bis (trifluoromethyl)-4,4'diamino biphenyl (TFMB/TFDB) to produce poly(amic acid) (PAA). Then, PI fibers were fabricated using the wet-spinning and imidization processes. To optimize the draw ratio, the elongation of PI fibers were executed between glass transition temperature (Tg) and melting temperature (Tm) with temperature. To investigate the physical and thermal properties of spinning PI fibers, thermogravimetric analyzer (TGA) and favimat + (Textechno) were used, and scanning electron microscope (SEM) and 3D digital microscope (3Ddm) were used to observe the morphologies of PI fibers.