In our recent study, we reported that kurarinone, one of the most abundant flavonoids found in the dry root of Sophora flavescens (Kushen), is a potent activator of the large-conductance Ca²⁺-activated K⁺ (BK_Ca) channel. Herein, we isolated and characterized other flavonoid components from Kushen. Among the 13 compounds tested, six flavonoids were found to activate the BK_Ca channel, three of which, 7,4′-dihydroxy-5-methoxy-8-(γ,γ-dimethylallyl)-flavanone, kuraridin, and kuraridinol, are new activators of the BK_Ca channel.