The invention discloses a drug for invigorating the spleen of a child to arrest diarrhea and suitable for rectal infusion and a preparation method of the drug, belongs to a traditional Chinese medicine preparation and a preparation method thereof, and particularly relates to the drug for invigorating the spleen of the child to arrest diarrhea and suitable for rectal infusion and the preparation method of the drug. The drug is mainly prepared from the following materials in parts by weight: 13-16 parts of roasted white atractylodes rhizome, 10-13 parts of tuckahoe, 11-14 parts of Chinese yam, 9-12 parts of semen coicis, 9-12 parts of white bean, 8-10 parts of platycodon grandiflorum, 5-7 parts of wrinkled giant hyssop, 9-12 parts of semen plantaginis, 5-7 parts of myrobalan, 5-7 parts of myristica fragrans, 5-7 parts of pomegranate bark, and 5-7 parts of rhizoma zingiberis. The drug has the beneficial effects that the dispensed medicine prepared by traditional Chinese medical science is available in materials, simple in preparation method, low in price, and definite in curative effect, plays the roles of invigorating spleen, promoting dieresis and stopping diarrhea, harmonizing the spleen and stomach, and achieving the treatment target by rectal absorption, and is a novel drug for treating splenasthenic diarrhea of children at present.