Abstract: Objective To screen drug-resistance related proteins through analysis of comparative differential proteins expression in human lung adenocarcinoma cell lines A549 and A549/DDP. Methods Comparative two-dimensional electrophoresis (2-DE) technology was performed to separate the total protein of the two cell lines. Differential proteins between A549 and A549/DDP cell lines were identified by Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS). Furthermore,essential proteins were confirmed by ICC (Immunocytochemistry). Results The well-resolved, reproducible 2-DE patterns of A549 and A549/DDP were established. Thirteen differential proteins were identified by peptide mass fingerprinting (PMF). These proteins were related with cellular metabolic, structure, detoxification or repair of DNA damage and signal transduction. Conclusion There were differentially expressed proteins in A549/DDP cells, which might related with DDP resistance. The study might provide information for drug resistence study.