The invention discloses a formula milk powder for pregnant and lying-in women and a preparation method thereof. The formula milk powder comprises: 30%-55% of skimmed milk powder, 30%-55% of whole milkpowder, 1%-8% of inulin, 1%-8% of galactooligosaccharide, 1%-6% of hydrolyzed whey protein powder, 0.2%-1.2% of calcium carbonate, 0.1%-1.1% of docosahexaenoic acid grease, 0.1%-1% of lactose, 0.1%-0.8% of minerals, 0.1%-0.7% of vitamins and 0.02% of bifidobacterium lactis HN019 freeze-dried powder. According to the formula milk powder, the inulin and the galactooligosaccharide serve as strengthening factors of the Bifidobacterium lactis HN019, the concentration of the Bifidobacterium lactis in excrement of pregnant women is increased, constipation is prevented or relieved, intestinal peristalsis is stimulated, excrement wettability is improved, intestinal flora balance and intestinal health are maintained, and absorption of vitamin B1, zinc and other microelements by pregnant and lying-in women is improved. Experimental results show that after the milk powder is eaten, the concentration of Bifidobacteria in the excrement of the pregnant women reaches 10<10> cfu/g or above, and the concentration of the Bifidobacteria in intestinal tracts is obviously increased. The formula and the process of the milk powder can also effectively improve the problem of wall adhesion in a spray drying stage.