A novel forming method "micro hydromechanical deep drawing (MHDD)" is focused to improve the tribological property and forming limit. In this study, a theoretical model for MHDD is developed to investigate the size effect on deformation behavior in micro hydromechanical deep drawing. The effects of fluid pressure, the difference of friction coefficients at inner pockets and outer pockets are considered in the investigation on the size effect of tribological property. The friction force decreases as the scale factor decreases in MHDD process. It is also found that the tribological property in micro scale can be improved by applying the fluid pressure. The forming limit decreases as the relative punch diameter increases. However, it is clarified that the forming limit can be improved by decreasing the friction force in MHDD.