Abstract: Changes of Ca²⁺ and Ca²⁺-ATPase in the mesophyll cell of Euonymus japonicus‘Cuzhi’at 4 ℃were investigated with electromicroscopic-cytochemical methods of calcium antimonate and lead nitrate precipitate. It is shown in the evidences that，compared with that of the plant at room temperature，the number of calcium particles in intercellular spaces and vacuoles of the mesophyll cell decreased，but that in the cytoplasm significantly increased at the early stage（at 4 ℃ from 3 hours to 12 hours）. However，there was almost no changes of Ca²⁺-ATPase distribution. The plasma and vacuoles membrane showed high activity of Ca²⁺-ATPase simultaneously. After 24 hours at 4 ℃，Ca²⁺ in cytoplasm and nucleus which increased before began to go back to the intercellular spaces and the vacuoles，Ca²⁺-ATPase activity on plasma and vacuoles membrane was enhanced. At 4 ℃ from 48 hours to 96 hours，Ca²⁺ concentration in the cytoplasm restored to the lower resting level，the same as that before the cold stress，yet the plasma and vacuoles membrane still showed high activity of Ca²⁺-ATPase. Thus it could be concluded that there is certain relativity between Ca²⁺ homeostasis and dynamic changes of Ca²⁺-ATPase with the plant cold resistance.