Abstract: Protein kinase has the potential catalytic ability and can transfer γ- phosphate group of ATP to specific amino acid residue of protein substrate ,thereby phosphorylates the target protein. According to specificity of the amino acid on the substrate, protein kinase can be subdivided into serine/threonine kinase and tyrosine kinase. Protein kinase plays an important regulating action during DNA replication and mitotic process. Protein kinase also plays an important role in the transcription process, such as the nuclear translocation of transcription factors, regulation of binding of transcripttion factors to DNA and activation of transcription factors. There is a close relationship between phosphorylation of protein kinase and tumorigenesis, then it can make a series of cell response happened as the change of gene expression and so on, eventually lead to the occurrence and development of cancer.