OBJECTIVE： To establish a method for rosmarinic acid in Herba Rabdosiae Serrae. METHODS： HPLC method was performed on the column of Inertsil ODS-SP C18 with mobile phase of acetonitrile-0.4％ phosphoric acid （gradient elution） at a flow rate of 1.0 ml/min， the detection wavelength was 327 nm， column temperature was 25 ℃， and injection volume 10 μl. RESULTS：The linear range of rosmarinic acid was 5.039-100.776 μg/ml（r＝0.999 6），RSDs of precision， stability and reproducibility tests were lower than 3％； recovery was 99.53-104.38％（RSD＝2.06％，n＝9）. CONCLUSIONS： The method is simple with good reproducibility and high accuracy， and can be used for  the content determination of  rosmarinic acid in Herba Rabdosiae Serrae.