Three new glycoalkaloids, N-formyl-asimilobine-2-O-beta-D-glucoside (1), (-)-1-O-beta-D-glucoside-8-oxotetrahydropalmatine (2), and 1-N-monomethylcarbamate-argentinine-3-O-beta-D-glucoside (3) were isolated from tubers of Stephania succifera. The structures were established based on spectroscopic analysis, and the antimicrobial activities of the three glycoalkaloids are reported.