Abstract: Seventeen phenolic compounds were isolated from the aqueous extract of the stems of Ephedra sinica using various column chromatographic techniques, including silica gel and Sephadex LH-20, combined with semi-preparative HPLC. Their structures were elucidated by modern spectroscopic methods such as NMR, UV, IR, and MS. Compounds 1 and 2 were identified as new phenols, and compounds 3-17 were isolated from this plant for the first time. The proliferation inhibitory activities of all the compounds on human non-small cell lung cancer cells (A549) was screened. The results showed that compounds 1-17 exhibited no proliferation inhibitory activity on A549 cells at a concentration of 10 μmol·L^-1.