The invention relates to a Chinese medicinal herb additive for preventing post-weaning diarrhea and a pig feed thereof of the technical field of medicaments. The additive comprises the following components in part by weight: 30 to 60 parts of pilose asiabell root, 20 to 40 parts of largehead atractylodes rhizome, 30 to 60 parts of Indian buead, 20 to 40 parts of white hyacinth bean, 30 to 60 parts of cinnamomvine, 20 to 40 parts of semen nelumbinis, 20 to 40 parts of Job stears, 10 to 30 parts of villous amomum fruit, 10 to 30 parts of costustoot, 20 to 40 parts of root of rehmannia, 20 to 40 parts of Chinese angelica, 20 to 40 parts of peony, 15 to 30 parts of Szechuan lovage rhizome, 30 to 90 parts of scorch-fried medicated leaven, 30 to 90 parts of scorch-fried malt, 30 to 60 parts of scorch-fried hawthorn fruit, 40 to 80 parts of dragon bone, 40 to 80 parts of oyster, 10 to 30 parts of platycladi seed, 10 to 30 parts of spiny jujube kernel, 10 to 30 parts of anemarrhena asphodeloides bunge, 20 to 40 parts of platycodon root, 20 to 40 parts of semen perillae acutae, 20 to 40 parts of white mulberry root-bark, 30 to 60 parts of cyrtomium rhizome, 30 to 60 parts of tuber tuber fleeceflower root, 30 to 60 parts of epimedium Herb, 20 to 40 parts of gambir plant, and 6 to 18 parts of liquoric root; and the additive accounts for 1.5 weight percent of the pig feed. The Chinese medicinal herb additive preventing the post-weaning diarrhea improves resistance to pathogenic escherichia coli of pigs.