The content of aristolochic acid I in asarum was determined by ultrasonic extraction with 70% methanol solution and HPLC-UV method. The detection limit was 0.20 ng. The recovery rate was 98.5%-103.5%. The detection method is simple, with good separation, high sensitivity, and good stability. Aristolochic acid I was not detected in the roots and stems of asarum, and the content in the leaves was 0.031 3-0.087 3 mg/kg, which was far below the pharmacopoeia limit of 0.001%, and the risk was very low.