The invention discloses a modified manufacturing process for a high-chromium cast iron composite roll through a forged steel roll neck and equipment. The material comprises, by mass, 3.0%-3.6% of C, 0.60%-1.20% of Si, 0.30%-1.20% of Mn, 3.0%-5.0% of Ni, 1.0%-2.0% of Cr, 0.40%-1.2% of Mo, 0.1%-2% of W, 0.5%-1.0% of Cu, 0%-0.05% of P, 0%-0.03% of S, 0.04%-0.06% of Mg, 0.1%-0.3% of Nb, 0.1%-0.30% of Ti, 0.2%-0.6% of V, 0.05%-0.2% of B, 1.5%-2.5% of Ba, 1%-2% of Ca, 1%-3% of Sb, 0.02%-0.18% of N, 1.0%-2.0% of Y/RE and the balance Fe and inevitable microelements. Yttrium-based rare earth nodulizing and compound inoculating of Ba, Ca and silicon iron are adopted, and modification treatment is conducted by adding Nb, Ti, V, B, and Sb, so that the mechanical property of the roll is improved. The strength of the roll is improved through the forged steel roll neck. Overall in-mold heating and fusion casting are conducted on a core rod through an induction heater. Forming is conducted through a water cooled crystallizer. A composite layer interface can be dynamically controlled. The process is simple, the efficiency is high, power consumption is small, the cost is low, composition segregation is avoided, and the service life of the roll is long.