Absorbent and antimicrobial fibers were prepared by coating chitosan on chemically modified polyacrylonitrile(PAN) fibers. PAN fibers were chemically modified by alkaline hydrolysis under different conditions, different concentrations, and temperatures. The transformation of nitrile groups to carboxylate groups was indentified by ATR-infrared spectroscopy and absorbency measurement. Absorbency of modified PAN increased with alkaline concentration and reaction temperature, while its tensile strength and modulus decreased. The modified PAN fibers coated with chitosan showed excellent antimicrobial activity against Staphylococcus aureus, compared with the original PAN. Additionally, the modified PAN fibers treated with chitosan showed high durability to laundering probably due to strong ionic interaction between chitosan and modified PAN.