The purpose of this study is to determine the content of chlorogenic acid in the medicinal herb (Eleutherococcus trifoliatus (L.) S.Y.Hu) harvested in Sin Ho district, Lai Chau province, using high-performance liquid chromatography (HPLC). In the study, the medicinal herb sample was extracted and processed using ultrasound, with a solvent comprising 5% formic acid solution in 50% methanol. The content of chlorogenic acid in the extract was quantified by HPLC under the following conditions: reversed-phase column (C18, 250 mm × 4.6 mm, 5 µm), a water-acetonitrile mobile phase (containing 0.1% phosphoric acid) at an 80:20 ratio, a sample injection volume of 20 µL, a flow rate of 0.8 mL/min, and a detection wavelength of 327 nm. The analytical method was evaluated for its system suitability, specificity, linearity, and accuracy. The study reported a chlorogenic acid peak with a retention time of approximately 5.6 minutes. Quantitative methods met the criteria for specificity and system suitability. Accuracy had an average recovery rate of 99.8%. Linear ranges were established for chlorogenic acid concentrations between 18.7 µg/mL and 93.6 µg/mL, with a correlation coefficient (R²) of 0.9996. Applying the quantitative method, the chlorogenic acid content in the research sample was determined to be 0.0443 ± 0.004%.