The invention provides a nutrient supplement for first-delivery sows, and belongs to the technical field of breeding of first-delivery sows. The nutrient supplement comprises 100-200 parts of poly-isomaltose, 100-200 parts of baking soda, 50-100 parts of probiotics, 60-150 parts of chitosan oligosaccharides, 100-150 parts of L-Lysine monohydrochloride, 50-100 parts of methionine, 50-120 parts of calcium lactate, 0.1-0.3 part of zinc glycinate, 0.08 -0.12 part of manganese glycinate, 0.01-0.03 part of cupric glycinate, 50-100 parts of an acidulant, 150-200 parts of vitamin E, 10-15 parts of vitamin A, 2-3 parts of vitamin D3 and 10-500 parts of silicon dioxide. A preparation method of the nutrient supplement comprises the following steps of weighing the components in parts by weight, sequentially adding the components in parts by weight to a mixing machine in the sequence from the big components to the small components, performing uniform mixing, and performing subpacking with a non-toxic bag. According to the nutrient supplement, the physical development of the first-delivery sows can be promoted, the firstborn stress of the first-delivery sows can be reduced, the body storage of the first-delivery sows can be strengthened, the food consumption of the sows at the early period of a lactation period can be increased, the disease resistance of the first-delivery sows at a perinatal period can be strengthened, the syndromes of the sows for second pregnancy can be alleviated, the service life of the sows can be prolonged, and the rejection rate of the sows can be reduced.