The invention discloses an itaconic acid derivant for copolymerization of acrylonitrile. The structural general formula (I) of the itaconic acid derivant is as follows: in the formula (I), R1 is alkyl. The itaconic acid derivant with both ester-base and ammonio is adopted as a comonomer for the acrylonitrile and the conventional ternary polymerization is replaced, so that the controllability of a copolymer is improved. The itaconic acid derivant is used for preparing high-performance PAN raw silks. In the copolymer of the acrylonitrile and the itaconic acid derivant, the mass ratio of the acrylonitrile is within 90 to 99.99%, and the mass ratio of the itaconic acid derivant is within 0.01 to 10%. The number-average molar mass of the copolymer is within 1 to 1 million.