The invention provides an alloy material for an incinerator fire grate and a preparation method of the alloy material, and belongs to the field of manufacturing and processing of special alloy materials. The alloy material for the incinerator fire grate comprises the following alloy elements in percentage by weight: 0.15 percent to 1.5 percent of carbon C, 2 percent to 3 percent of silicon Si, 0.6 percent to 1.5 percent of manganese Mn, 18 percent to 29 percent of chromium Cr, 2.5 percent to 4.0 percent of nickel Ni, 0.15 percent to 0.45 percent of molybdenum Mo, 0.1 percent to 0.8 percent of copper Cu, 0.05 percent to 0.20 percent of rare earth element RE, less than or equal to 0.03 percent of sulfur S, less than or equal to 0.04 percent of phosphorus P, 0.1 percent to 0.3 percent of nitrogen N, 0.05 percent 0.40 percent of strong carbide forming element, 0.04 percent to 0.06 percent of boron B, 0.04 percent to 0.06 percent of aluminum Al, and the balance of ferrum Fe and other inevitable impurities. The alloy material for the fire grate provided by the invention has the characteristics of high temperature resistance, corrosion resistance, carbonization resistance, wear resistance and the like, is simple in process, long in service life and good in comprehensive performance, is very suitable for materials for fire grates of large municipal solid waste incinerators in China, and has a wide application prospect.