Free-radical solution copolymerization of itaconic acid and acrylonitrile was carried out in DMSO at 58～60℃ using azodiisobutyronitrile as initiator．The resulting polymerization solution was spun to form PAN precursors of carbon fibres．The precursors were treated with NiSO4 aqueous solution at 95℃ on line．The structure and properties of untreated and treated PAN precursors and resultant carbon fibres were characterized by IR

SEM

dynamic viscoelasticity study

stabilization process and so on．It was suggested that carbon fibres developed from modified PAN fibres showed an improvement in tensile strength by about 20％～30％ and Young’s modulus by about 5％～10％.