Calcium in Red Fuji and Starkrimson apples during storage were fractionated by sequentextracting. Localization and distribution of calcium and influence of calcium nutritionon cell ultrastructure were observed by transmission electron microscopy combined within situ precipitation of calcium with an improved method of potassium pyroantimonatetechnique. Results indicated that spraying calcium solution on surface of young fruitsincreased contents of calcium in all forms. During storage, contents of soluble calciumand pectic calcium declined and those in calcium phosphate, calcium oxalate and calciumsilicate increased. Calcium contents of Red Fuji in all forms were higher than those ofStarkrimson, indicating that calcium accumulating capability of Red Fuji fruits precededthat of Starkrimson. Under transmission electron microscopy, calcium antimonite precipitates(CaAP) was mainly distributed in cell wall, tonoplast, nuclear membrane and nucleoplasm,much more CaAP deposited in vacuole. Calcium deficiency during storage leads to decreaseof CaAP in locations mentioned above, disappearance of compartmentation, and entrance ofCaAP to cytoplasm. Transformation from soluble calcium and pectic calcium to calciumphosphate, oxalate and damages of biomembranes structuraly and functionally resultedfrom calcium deficiency during storage were the crucial causation of physiologicaldisorder. Calcium in Red Fuji and Starkrimson apples during storage were fractionated by sequentextracting. Localization and distribution of calcium and influence of calcium nutritionon cell ultrastructure were observed by transmission electron microscopy combined within situ precipitation of calcium with an improved method of potassium pyroantimonatetechnique. Results indicated that spraying calcium storage on surface of young fruits created contents of calcium in all forms. During storage, contents of soluble calciumand pectic calcium declined and those in calcium phosphate, calcium oxalate and calcium silicate increased. Calcium contents of Red Fuji in all forms were higher than those of Starkrimson, indicating that calcium accumulating capability of Red Fuji fruits precededthat of Starkrimson. Under transmission electron microscopy, calcium antimonite precipitates (CaAP) was mainly distributed in cell wall, tonoplast, nuclear membrane and nucleoplasm, much more CaAP deposited in vacuole. Calci um deficiency during storage leads to decrease of CaAP in locations mentioned above, disappearance of compartmentation, and entrance of CaAP to cytoplasm. Transformation from soluble calcium and pectic calcium to calciumphosphate, oxalate and damages of biomembranes structuraly and functionally derivedfrom calcium deficiency during storage were the crucial causation of physiologicaldisorder.