The mechanical interactions between mononuclear cells of human cord blood and ice crystals are tested with the cryo-microscope during freezing,under the condition of adhering different cryo-protective additives(CPA).The ice crystals' formation and growth characteristics during freezing whether with an external static electric field or not are investigated so as to change the interaction manner between the cells and crystals.It is found that there exist certain mechanical interactions between the cells and crystals and the external static electric field may affect the formation and growth characteristics of ice crystals.It can make the crystals thinner to some extent.With different CPA,the restraining effect on the ice crystals is distinct due to the different chemical mechanisms.