Abstract: The dosage of asarum in Qing-Fei-Pai-Du decoction (QFPD) is twice the dosage prescribed by the Chinese Pharmacopoeia. Due to the potential toxicity of aristolochic acid I (AAI), a limited component in asarum, the possibility that its dosage also exceeds the dosage prescribed by the Chinese Pharmacopoeia had aroused wide concern. In this study, the UHPLC-Q TOF method was used to determine the presence of AAI in QFPD. A UHPLC-QQQ method was then established to determine the content of AAI in QFPD, a reflux extract of asarum and an ultrasonic extract of 70% methanol of asarum. The results showed that the amount of AAI in the three samples was approximate 1.5, 3.2 and 9.0 μg respectively with equivalent dosages of asarum (6 g). All were obviously lower than the maximum daily limit stipulated in the Chinese Pharmacopoeia (30 μg). Therefore, we concluded that the content of AAI could be effectively reduced by using a Chinese herbal compound decoction and optimization of asarum. This assay is not only convenient, rapid, sensitive and reproducible for the trace detection of AAI in Chinese herbal compound decoction, but also useful for the rational application of asarum in QFPD.