The invention provides high-toughness bainite wear-resistant steel suitable for a liner plate of a large semi-autogenous mill. The high-toughness bainite wear-resistant steel is prepared from, by masspercent, 0.4% to 0.8% of C, 1.4% to 2.5% of Si, 0.7% to 1.6% of Mn, 1.5% to 2.5% of Cr, 0.2% to 0.7% of Mo, 0.01% to 0.05% of Nb, 0.1% to 0.5% of Cu, 0.1% to 0.5% of Ni, 0 to 0.03% of Al, 0.01% to 0.2% of RE, 0.008% to 0.015% of N, not larger than 0.015% of P, not larger than 0.01% of S, not larger than 0.004% of O and the balance Fe and inevitable impurities. A preparation method is further provided, and comprises the steps that a thick plate formed through smelt forging or rolling is subjected to spheroidizing annealing and heat treatment; and the obtained wear-resistant steel contains nanoscale or submicron-scale carbide-free bainite, thin-film-shaped bainite and a small amount of blocky bainite.