Escherichia coli is the first bacteria on which cloning and protein expression are carried out. The purpose of this study was to summarize the numerous articles published in the field of protein expression in Escherichia coli. In studies, researchers in a new project require the production of pure protein, which at the theory level is easy to obtain a recombinant protein, but there are virtually many problems, including low growth of host, formation of inclusion, protein not being active, and there is even no protein production in the exprimental scale. To enhance the expression of the protein, factors such as suitable host, vector design, transcriptional settings, selective markers, and reluctant labels are effective. There are a range of fusion proteins that can effect on accurate folding, solubility, and proteolytic resistance. Also the ability to target produced proteins to cytoplasm, periplasm, membranes and the culture medium, and some techniques grant the ability of post translational modifications in prokaryotic cells. Therefore, the key to the successful expression of recombinant proteins in E. coli is a combination of expert manipulation of the components of a broad genetic apparatus.