To study the relationship between alkaloids contents in Chinese traditional drug Yimu Cao (the dried aerial parts ofLeonurus artemisia) and its growing environment. Methods: Samples of the drug and the soil at the growing site collected from 5 selected regions. Reference materials were checked and on-the-spot observations were carried out to investigate the growth environment. RP-HPLC was performed to determine the alkaloid contents in the drug. Results: Different regions had different environmental conditions, including climate, soil, vegetation, and so on.No matter barren or fertile the soil at the growing site was, the herb ofL. Artemisia could grow well, but the contents of alkaloid in the drug varied greatly. The drugs produced in 2 north regions, where the soil is alkaline, had higher content of alkaloid (about 0.4%) than that produced in south regions (0.1%-0.2%), where the soil is acid. Conclusion:The contents of organic matters, effective phosphorus, quick-acting potassium, and the pH value of the growing site soil were the factors correlating with alkaloid contents in the drug, among which the pH value of soil was an important positively correlating factor. The alkaline soils in North benefit the accumulation of alkaloids more than the acid soils in South. The other probable elements affecting the alkaloid contents in Yimu Cao were climate and genetic factors.