Biomarkers are the core of today's drug development, especially in the field of tumor. Clinical studies using biomarkers have a higher success rate of drug development than those without biomarkers.Biomarkers are important tools to improve the efficiency of drug development. The exploration of biomarkers with different functions should run through the early development, preclinical research and the whole clinical development stage.The functions of biomarkers are different. Biomarkers should be reasonably selected and used according to the application purposes of different drug development stages.