Abstract: The rotigotine in beagle dog plasma was determined by liquid chromatographic-tandem mass spectrometry. The method of HPLC-MS/MS was used, and detection was performed on a tandem spectrometry in multiple reaction monitoring(MRM) mode. The standard curves are linear in the range of 0.025-12.5 μg L^－1, and the recovery is 89%-91%, the intra-day and the inter-day precision are less than 5.6% and 6.8%, respectively. The low limit of quantification(LLOQ) is 0.025 μg L^－1. The specificity is good and sensitive, so this method is suitable for the parmacokinetical research of rotigotine.