AbstractIn this work, the subcritical water extraction technology was used to extract alkaloids from Macleaya cordata, and the effects of extraction temperature and time on its yield were investigated to find the best extraction conditions. Moreover, the antioxidant capacity and antibacterial activity of Macleaya cordata extract were studied. Furthermore, through the single‐factor method, it was found that properly increasing the extraction temperature and prolonging the extraction time was conducive to increasing alkaloid yield. Still, a considerable amount of alkaloids might be decomposed by heat, resulting in a decrease in their yield. The results showed that the optimal extraction temperature of alkaloids from Macleaya cordata with subcritical water is 190 °C, the time is 45 min, and the corresponding maximum yield is 35.19±0.12 mg/g (sanguinarine equivalent in raw materials). In addition, the antioxidation and bacteriostasis abilities of subcritical water extract are better than those of traditional hot water extract, indicating that it is a feasible method to extract alkaloids from Macleaya cordata with subcritical water.