The invention provides a protein synthesis system for in-vitro protein synthesis, a kit and a preparation method for a protein through in-vitro synthesis. Specifically, the in-vitro cell-free expression system provided by the invention is capable of extremely efficiently synthesizing proteins and synthesizing complex proteins. Moreover, due to the in-vitro cell-free expression system disclosed bythe invention, the relative light unit value of the activity of the synthesized luciferase is higher than that of the conventional commercial system (such as a rabbit reticulocyte in-vitro expressionsystem) by at least one order of magnitude (more than or equal to 10 times or higher).