Macleaya cordata is rich in alkaloids and exhibits diverse biological activities, which explains its worldwide distribution and utilization. This paper provides an overview of those alkaloids, their solubility and stability, as well as various biological activities, including antibacterial, anti-inflammatory, anticancer, and insecticidal properties. It also focuses on research into Macleaya cordata and on the application of that plant and its bioactive components in the pig industry as potential alternatives to antibiotics in feed, as well as in prevention and treatment of diseases, especially diarrhea. This paper reviews the alkaloids contained in Macleaya cordata, their biological characteristics and application in the pig industry, hoping to provide a valuable reference for further research on the utilization of Macleaya cordata and its bioactive ingredients in the pig industry and in animal husbandry in general.