Xiatianwu (XTW) Injection, derived from Corydalis Decumbentis Rhizoma, is clinically utilized to promote circulation and alleviate pain. However, its effective components and pharmacokinetic profile have yet to be elucidated. In the present study, 46 components, including 32 alkaloids, were identified in XTW Injection, of which 19 alkaloids were also detected in post-dose rat plasma by UPLC-QTOF analysis. Then a UPLC-QqQ assay was developed to determine ten alkaloids (corydalmine, corypalmine, columbamine, jatrorrhizine, palmatine, tetrahydropalmatine, protopine, allocryptopine, muramine, bicuculline) in rat plasma. Chromatographic separation was achieved on an ACQUITY UPLC HSS T3 column with 0.1% formic acid in water and acetonitrile as the mobile phases. The method showed satisfactory selectivity, linearity, matrix effects, precision, accuracy, and dilution integrity, and the samples showed sufficient stability. The validated method was successfully applied to the pharmacokinetic study in rats after acupoint administration of XTW Injection at three doses. The study revealed that most quantified alkaloids were rapidly absorbed. The Cmax and AUC0-t were positively related to the doses. Protopine, tetrahydropalmatine, and bicuculline showed higher plasma exposure, while tetrahydropalmatine, corypalmine and bicuculline exhibited higher dose-normalized Cmax and AUC0-t. Metabolites of the higher-exposure alkaloids (protopine, tetrahydropalmatine, and bicuculline) were tentatively identified by UPLC-QTOF in rat plasma, urine, bile, and feces, with 19, 25, and 7 annotated metabolites, respectively, formed mainly via O-demethylation, demethylenation, or hydroxylation, followed by glucuronidation or sulfation. This study will contribute to elucidating potential active components, the pharmacological mechanisms, and providing a basis for dose optimization.