The copolymer made from AN, VAc and TAM can be spun to polyacrylonitrile fibers which can be dyed with acid dyes, and the dye-uptake of the fiber can be up to 90 %. Through DSC and SEM analysis, the results reveal that the increase of disorder structure and hydrophile of TAM in this kind of fiber are very useful for its function with acid dyes. Furthermore, the dye-uptake improves.