The invention provides an alloy composition, comprising the following components in percentage by weight: 0.3-0.5% of C, 0.5-0.8% of Si, 0.7-1.3% of Mn, less than or equal to 0.025% of P, less than or equal to 0.025% of S, 1.5-3% of Cr, 0.2-0.4% of Mo, 0.15-0.35% of Ni, 0.005-0.020% of Ti, 0.1-0.35% of Cu, 0.001-0.006% of B, 0.02-0.07% of La, less than or equal to 0.03% of Al and the balance of Fe. The invention further provides a semi-autogenous mill lining plate made of the alloy composition and a manufacturing method of the lining plate. The semi-autogenous mill lining plate disclosed by the invention has excellent mechanical property and good abrasion resistance, so that the overhauling frequency is reduced, repeated work is avoided, the labor intensity is reduced, the service life of equipment is prolonged, and the economic benefit is improved.