Abstract: Principle of similarity between the electrohydromechanic process of continuousflow electrophoresis carried out in space and that of ground-based mimicking was established by similitude analysis. Numerical simulation demonstrated the effectiveness （approximate） of this treatment. Based on these theoretical works, groundbased experimental system mimicking the electrohydromechanic process of continuous-flow electrophoresis in space was developed and used for separation of biological samples, and of course, final test of the principle of similarity depends on space experiments.