Abstract: This application provides a polyimide fiber and a preparation method thereof. This method comprises first subjecting a dianhydride compound and a diamine compound to a polymerization reaction in a solvent to obtain a polyamic acid solution, wherein said diamine compound comprises a diamine having a structure of Formula 12 or Formula 13, wherein A is S or O; said dianhydride compound comprises one or more of dianhydrides having structures of Formula 14 and Formula 15; and t is 0 or 1; then subjecting said polyamic acid solution to spinning to obtain a polyamic acid fiber; and sequentially subjecting said polyamic acid fiber to imidization and thermal drawing to obtain a polyimide fiber. The polyimide fiber having the above structure has a higher rigidity and can introduce a hydrogen bond to provide an interaction between molecular chains so as to influence the arrangement of the molecular chain in the polymer and the crystallinity, which imparts more excellent mechanical properties to the polyimide fiber.

Abstract: This disclosure provides a polyimide fiber prepared from a dianhydride compound and a diamine compound, wherein said diamine compound is selected from one or more of the compounds represented by the following formulae (I), (II), (III) and (IV). A polyimide fiber is prepared by using a polyimide polymer system having a specific hydroxyl heterocyclic diamine copolymerization structure, and the prepared polyimide fiber has relatively high strength and modulus and is resistant to high temperature. Furthermore, the polyimide fiber prepared by this disclosure is provided with an active group on its surface, thus being easily adhered to various resin matrices, and the composite material prepared has good mechanical properties.