Lung cancer is the leading cause of death after liver cancer but it trends to be increased because it is hard to detect the symptoms of a disease in the first stage. Survival rate of the patient is up to the stage of the cancer. Researcher had tried to develop the methodologies for early detection of cancers. Proteomic analysis technique is selected. This research aimed to understand the expression of proteins from lung cancer cell line (A549) and compare with normal lung fibroblast cell line (MRC-5). The phosphoproteins were the major target of investigation by using proteomic analysis technique. The results were indicated that there were several proteins which present and absent in lung cancer cell line. Some proteins were difference in term of quantitation. The most of proteins which over-expressed in lung cancer cell line (A549) were phosphoproteins such as Lamin AC 70 kDa, Aldehyde dehydrogenase, α-enolase, Glyceraldehydes-3-phosphate dehydrogenase, Pyruvate kinase, Peroxiredoxin. Moreover some proteins were expressed only in lung cancer cell line (A549) such as Heterogenous ribonucleoprotein A1, Heterogenous ribonucleoprotein H1, Nuclear corepressor KAP1, Transketolase and Cytokeratin18. Furthermore, Chaperonin which is phosphoprotein was found. This protein functions on protein interaction and protein conformation. The over-expression of this protein in cells may cause abnormality of protein conformation and lead to early stage of cancer. Then this protein may be used as biomarker of lung cancer for early detection and clinical prognosis. Further studies on this topic are required.