Two new thiazinediones along with five known compounds were isolated from the fruits of Xanthium strumarium L. The structures of the two new compounds were determined to be 7-hydroxymethyl-8,8 dimethyl-4,8-dihydrobenzol[1,4]thiazine-3,5-dione-11-O-β-D-glucopyranoside (1) and 2-hydroxy-7 hydroxymethyl-8,8-dimethyl-4,8-dihydrobenzol[1,4]thiazine-3,5-dione-11-O-β-D-glucopyranoside (2). The five known compounds were identified as xanthiazone (3), chlorogenic acid (4), ferulic acid (5), formononetin (6), and ononin (7), respectively.