The invention provides a microalloying high-strength gray pig iron piece and a smelting method thereof and relates to the field of metal casting. The gray pig iron piece comprises, by weight percent, 2.92%-3.48% of C, 1.52%-2.36% of Si, 0.22%-0.78% of Mn, 0.15%-0.5% of Cr, 0.3%-0.78% of Cu, 0.011%-0.098% of Nb, 0.02%-0.1% of V, 0.015%-0.025% of Ti and the balance iron and other traces of unavoidable impurities. A casting piece base body is intensified through microalloying, the intensity and the rigidity of the casting piece are improved, a high-efficiency nucleating agent is added, graphite form, hardness and texture uniformity can be effectively improved, the sensibility is reduced, the mechanical performance of the gray pig iron piece is improved, by adopting the in-mold inoculation manner, the utilization rate of the nucleating agent can be improved, the inoculation effect is improved, and the cost is reduced.