Objective: To explore the effect of the traditional Chinese medicine Yifei Kangliu (YFKL) Oral Liquid on the proliferation, cell cycle and protein-nucleic acid synthesis of murine Lewis lung cancer cell and human lung adenocarcinoma cell line SPC-A-1. Methods: The inhibiting rates of tumor growth were calculated by weighing the weight of tumor inoculated in vivo, combined by counting cancer cells in vitro. The ratio of the cell cycle and exponents of DNA, RNA, and protein were measured by flow cytometry (FCM). Results: The inhibiting rate of tumor growth in the treated group with YFKL Oral Liquid was 30.38% (P<0.05). The proportion of cells in S phase of the treated groups with YFKL Oral Liquid was lower than that of the control group. In the group with most significant result, 72% of the cells were stagnated in G0/G1 phase. The inhibiting rates of DNA, RNA and protein in murine Lewis lung cancer were 7.4%, 23.73% and 23.31% respectively. In SPC-A-1 cell line, the inhibiting rates were 9.3%, 10.1% and 14.7% respectively, demonstrating amplified effects on lower levels. Conclusion: YFKL Oral Liquid significantly inhibited the proliferation of murine Lewis lung cancer cell and human lung adenocarcinoma cell line SPC-A-1 by blocking the cancer cells entering the proliferative phase resulted from its inhibition of DNA.