Objective: To establish the method for content determination of baicalin and related substances in baicalin chemical raw material. Methods: High performance liquid chromatography (HPLC) was used in this study, the mobile phase of baicalin and related substances were respectively methanol-water-phosphoric acid (47:53:0.2) and methanol-water-phosphoric acid (42:58:0.2), the detection wavelength was all 280nm. Results: The linear range of baicalin was 10.6922µg/ml~106.922µg/ml, the average recovery rate was 99.7% (RSD=0.96%). The baicalin content in 3 batches baicalin chemical raw material were respectively 89.9%, 91.2% and 90.7%. Specific test showed that the resolution and detection sensitivity of measuring system for related substances all reach the testing requirement. Conclusions: The method for determination of principal component and related substances by HPLC in this study is rapid, simple and specific, and suitable for the quality control baicalin chemical raw material.