Abstract: Foreign protein expression technology can be used in a variety of downstream applications, such as protein-protein interaction analysis, gene regulation analysis, protein structure and function analysis, etc. Considering the functionality, solubility, speed and yield of recombinant proteins, the correct choice of protein expression system is of great significance for the success of the experiment. This paper briefly introduced the common prokaryotic expression system, eukaryotic expression system, and their optimization and application in order to provide some technical support for the research and production of researchers.