Objectives The effects of soybean oligopeptides on the growth of Lactobacillus acidophilus were studied to provide ideas for the colonization in vivo of Lactobacillus spp. Method Different concentrations of soy oligopeptides were added to the MRS broth medium in the experimental group, and Lactobacillus acidophilus was cultured for 48 hours to measure OD_{600 nm}. The OD_{600 nm} of Lactobacillus acidophilus culture solution at different cultured times was measured to plot the growth curve. Mice with intestinal microbiota disorder induced by antibiotics were continuously gavaged with soybean oligopeptides-Lactobacillus acidophilus suspension at doses of 300, 600, and 1 200 mg/kg for 7 days. The changes in body weight of mice under the action of soybean oligopeptides were determined. Results 40, 30, and 20 mg/mL soy oligopeptides significantly increased the turbidity of Lactobacillus acidophilus, promoted its proliferation, enabled Lactobacillus acidophilus to enter a logarithmic growth phase after 12 hours of culture and enter a rapid growth state in advance, and increased the growth rate. The low-dose group of 300 mg/kg, the medium dose group of 600 mg/kg, and the high-dose group of 1 200 mg/kg all promoted the weight gain of mice. The body weight of the medium dose group of 600 mg/kg increased by 2.89 g, which was significantly different from the control group. Conclusions Soybean oligopeptides can significantly promote the proliferation in vitro of Lactobacillus acidophilus, and the proliferation effect is most significant when the concentration of soybean oligopeptides added is 40 mg/mL. Adding soybean oligopeptides can promote the weight gain of mice, but its mechanism of promoting the colonization in vivo of Lactobacillus acidophilus needs further evaluation.