In this paper, the antitussive and expectorant activity of platycodin D (PD) were studied by constructing a mouse cough induced by concentrated ammonia water and a mouse trachea phenol red excretion model. The mechanism of antitussive and expectorant effect of PD was studied by metabolomics. The animal experiment was approved by the Animal Ethics Committee of Jiangxi University of Chinese Medicine (approval number: JZLLSC-20220739). Then mice were randomly divided into the normal, model, positive drug, PD low-dose, PD medium-dose and PD high-dose group. The antitussive and expectorant effects of PD were evaluated using a cough mouse model induced by concentrated ammonia water and a mouse tracheal phenol red excretion model, respectively. UHPLC-LTQ-Orbitrap-MS was used to identify the metabolites of mouse lung tissue, and multivariate statistical analysis method of orthogonal partial least squares discriminant analysis (OPLS-DA) was used for metabolites profile analysis. The differential metabolites were screened by variable projected importance value (VIP) and t-test results. Pathways for enrichment of differentiated metabolites were analyzed using the MetaboAnalyst platform. The comparative method was applied to analyze the differences in mechanisms of PD, Deapio-platycodin D (DPD) and total platycosides fraction. The results showed that PD at different concentrations could significantly prolong (P < 0.05) the incubation period of cough mice induced by ammonia water, reduce the coughs frequency, and significantly increase (P < 0.05) the amount of phenol red excretion in phenol red excretion model mice. PD could regulate 6 metabolic pathways of phenylalanine, tyrosine and tryptophan biosynthesis, linoleic acid metabolism, phenylalanine metabolism, glycerophospholipid metabolism, and tyrosine metabolism to exert antitussive effect. It could also regulate 8 metabolic pathways of linoleic acid metabolism, glyoxylic acid and dicarboxylic acid metabolism, glycerol phospholipid metabolism, citric acid cycle and arachidonic acid metabolism to exert an expectorant effect. However, only linoleic acid metabolism and glycerophospholipid metabolism could be regulated by the PD, total platycosides fraction and DPD, which may be ascribed to the structural difference of the platycosides and the interaction between platycosides and the intestinal microbiota. Functional analysis showed that these metabolic pathways are closely related to the regulatory mechanisms of anti-inflammatory response, immune function regulation, neurotransmitter release, cell signal transduction, energy metabolism and cell apoptosis. This study shows that PD possesses good antitussive and expectorant activities. In addition, the mechanism difference of PD, total platycosides fraction and DPD imply that the apiose in PD and the interaction between PD and intestinal microbiota could exert an important effect on the antitussive and expectorant mechanism of the platycosides.