The proteomics definition, investigation method and its application in cancer research were simply introduced. Proteomic research is to reveal the function of genes from an integrated, kinetic and quantitative view at the global protein level, which is an important component of post-genome project. Cancer is a kind of complex disease involved by multi-genes. Proteomic research will be helpful to discover the mechanism of cancer development, to find special malignant tumor markers and targets of drug treatment.