Probiotics exert beneficial effects by regulating the intestinal microbiota, metabolism, immune function and other ways of their host. Patients with constipation, a common gastrointestinal disorder, experience disturbances in their intestinal microbiota. In the present study, we investigated the effectiveness of two microbial ecological agents (postbiotic extract PE0401 and a combination of postbiotic extract PE0401 and Lacticaseibacillus paracasei CCFM 2711) in regulating the makeup of the intestinal microbiota and alleviating loperamide hydrochloride-induced constipation in mice. We also preliminarily explored the mechanism underlying their effects. Both microbial ecological agents increased the abundance of the beneficial bacteria Lactobacilli and Bifidobacterium after administration and were able to relieve constipation. However, the degree of improvement in constipation symptoms varied depending on the makeup of the supplement. The postbiotic extract PE0401 increased peristalsis time and improved faecal properties throughout the intestinal tract of the host. PE0401 relieved constipation, possibly by modulating the levels of the constipation-related gastrointestinal regulatory transmitters mouse motilin, mouse vasoactive intestinal peptide, and 5-hydoxytryptamine in the intestinal tract of the host and by increasing the levels of the short-chain fatty acids (SCFAs) acetic acid, propionic acid, and isovaleric acid. It also increased the relative abundance of Lactobacillus and Bifidobacterium and reduced that of Faecalibaculum, Mucispirillum, Staphylococcus, and Lachnoclostridium, which are among the beneficial microbiota in the host intestine. Furthermore, PE0401 decreased the levels of constipation-induced host inflammatory factors. Therefore, the two microbial ecological agents can regulate the intestinal microbiota of constipation mice, and PE0401 has a stronger ability to relieve constipation.