An early-stage compound feed for broiler chickens comprises the following raw materials in parts by weight: corn 56-62, soybean meal 18-25, an enzymatically-decomposed and fermented rapeseed meal 3-9, bran 0-5, salt 0.3-0.4, lysine 0.4-0.5, methionine 0.2-0.5, grease 1-3, and a premix which does not contain a pharmaceutical additive 1-5, wherein the enzymatically-decomposed and fermented rapeseed meal is prepared by mixing rapeseed meal, a combination enzyme, plant lactobacillus solution, bacillus subtilis solution and water according to the proportion of the rapeseed meal, the combination enzyme, the plant lactobacillus solution, the bacillus subtilis solution and water being 75.5: 0.5: 1-3: 3-6: 15-20 by weight and allowing the raw materials to enzymatically decompose and ferment; the combination enzyme comprises neutral protease, pectinase, Beta-glucanase, xylanase, cellulose and mannanase. The preparation method of the early-stage compound feed comprises the following steps: uniformly mixing the above raw materials in the required proportions to obtain the mixture material, and subjecting the mixture material to pasting, palletizing and crushing in turn. The nutritional quality of the rapeseed meal is improved, and the production cost is reduced.