The invention relates to alloy steel smelting, and particularly relates to a chrome-molybdenum metal self reduction pellet and preparation and direct steel liquid alloying methods thereof. The pellet comprises the following components according to mass percentage: 40-65 percent of high-carbon ferrochrome powder, 15-40 percent of molybdic oxide powder, 5-15 percent of a reductant and 3-5 percent of a flux. The self reduction pellet product is added to a ladle during electric furnace or convertor tapping, under the action of high-temperature molten steel and a pellet inner reductant, metal elements in the pellet are effectively reduced, as a result, the molten steel is directly alloyed; the self reduction pellet product is applied in alloy steel including stainless steel, wear resistant steel and the like, which contain elements Cr and Mo, and not only is the procedure for the production of ferro molybdenum saved, but also the elements Cr and Mo can be added at one time, so that the cost of adding alloy elements is lowered, the smelting cycle is shortened, meanwhile, the use range of high-carbon ferrochrome is widened, and furthermore, the problem that the element Mo is difficult to add and settle and great in volatilization during the steel smelting is solved.