The major metabolites of ginsenoside-Rb1 in rats urine were described. Urine samples were collected before and after 24 h of single oral administration of 150 mg and intravenous administration of 60 mg Rb, to four rats, respectively. The samples were purified by SPE column and then were analyzed by liquid chromatography-ESI-mass spectrometry for potential metabolites. Parent drug and its fourteen metabolites were identified in rat urine based on the comparison of total ion chromatograms of the blank with the metabolic urine as well as mass spectra. Its main metabolic pathways and possible structures are analyzed in detail.