Previous clinical studies have shown good efficacy of the traditional Chinese medicinal herbal water extract Chan-Yu-Bao-Yuan-Tang (CYBYT) in lung cancer patients. In this study, CYBYT's effects on proliferation and apoptosis of human lung adenocarcinoma cell line SPC-A-1 cultured in vitro were explored. An XTT assay, cell cycle analysis, Annexin V-FITC staining and Western blot were applied to identify the viability of cells, cell cycle arrest, stages of apoptosis, and signaling proteins, respectively. The results showed that CYBYT inhibited the growth of SPC-A-1 cells by reducing the cells in G0/G1 phase but increasing them in S phase in a concentration-dependent manner, and inducing apoptosis, whereas it had no significant inhibitory effects on the normal human IMR-90 fibroblasts. Furthermore, early and total induction of apoptosis was positively correlated with the concentration of CYBYT in SPC-A-1 cells, and the rate of total apoptosis was greater in the CYBYT 100 µg/mL and 50 µg/mL groups than that of the positive control 5-fluorouracil (5-Fu) group. Moreover, CYBYT upregulated bax, cleaved caspase-3 protein expression, downregulated bcl-2 protein expression, and released mitochondrial cytochrome c into the cytosol in a time- and concentration-dependent manner. Our findings indicated that CYBYT could significantly inhibit growth and induce apoptosis via the mitochondrial pathway in human lung adenocarcinoma cell line SPC-A-1.