Lung cancer is by far the second most common cancer in both man and woman.It is also the leading cause of the cancer death.But no good clinical markers have been found that can be used to diagnose the disease before pathological examination.Metabonomics is a very useful tool to find candidate biomarkers.It concerns the study of low molecular weight compounds (typically < 1000 Da) in biofluids such as serum and urine.Recently, global metabolic profiling of human biofluids has been increasingly used as an effective tool for disease diagnosis to elucidate significant changes in tumor metabolism, to explore potential biomarkers from variance within a huge number of endogenous metabolites and to characterize the biological pathways.