mRNA display provides a new powerful tool for in vitro selecting of peptides and proteins. In the selecting process, peptides are covalently attached to their own mRNA to form mRNA-protein fusions. These mRNA-protein fusions enable in vitro selection of peptide and protein libraries of more than 10¹³ different sequences. The experiment conditions and protocols have been optimized in recent years. The application of mRNA display technology is mainly in the discovery of ligands for many kinds of target molecules and the analysis and mechanism elucidation on interaction between proteins. With its great potential, there will be a wide application foreground in the application of mRNA display.