The invention discloses a lotus root starch-containing low-protein premix for piglets and a preparation method of the lotus root starch-containing low-protein premix. The lotus root starch-containing low-protein premix is synthesized from fifteen raw materials including lotus root starch, corn meal, calcium carbonate, calcium hydrophosphate, salt, L-lysine, L-threonine, L-methionine, L-tryptophane, a vitamin additive, a microelement additive, choline chloride, piglet compound enzyme, a sweetening agent and an antioxidant. The preparation method comprises four processes of preparing the lotus root starch, preparing the corn meal (17), mixing and stirring, and bagging. The lotus root starch-containing low-protein diet premix prepared by adopting the technology is used for preparing a piglet mixed feed by using a proportion of 4 percent, the content of crude protein in the piglet mixed feed is reduced from internationally specified 20.00 percent to 17.00 percent, the consumption of the protein raw materials is reduced, the feeding cost is reduced, and the functions of reinforcing the stomach and tonifying the spleen, reducing the piglet diarrhea and decreasing the feeding cost are achieved.