Abstract: The Ca²⁺metabolism is one of vital factors relative to growth of shell and pearl in freshwater mussel.In order to probe the Ca²⁺absorption and transportation in freshwater shellfish,Ca²⁺ concentration of cells(under resting state)from different tissues and effect of Ca²⁺ concentration of culture medium on Ca²⁺ deposits within the cells from outer mantle were researched by technology of laser scanning confocal microscopy in Hyriopsis cumingii.The total of healthy 10 H.cumingii with pearl and without pearl were selected,and then the cells from their mantle,gill,foot and epidermis of visceral mass were isolated.After short-term culture,the cells were incubated using DMEM with different Ca²⁺ concentration(0,0.5,1.25,3 mmo1/L)and fluorescence probe of Fluo-3/AM for 1 h.The green fluorescence intensity was acquired to analyze the Ca²⁺ levels in these cells.The results showed that there were significant differences among intracellular Ca²⁺ fluorescent itensity of 5 kinds of cells(P<0.05):intracellular calcium ions fluorescent intensity of the outer mantle cells was highest(P<0.05),while intracellular Ca²⁺ fluorescent intensity of visceral mass epidermal cells was the lowest(^P<0.05).The intracellular Ca²⁺ fluorescence intensity of mantle cells in mussel with pearl mussel had increasing trends compared to that in mussels without pearl under the same Ca²⁺ level,and the difference was significant between the two groups of inner mantle with 1.25 mmol/L Ca²⁺level(P<0.05).Influence of different Ca²⁺ incubation levels on intracellular Ca²⁺fluorescence intensity were significant(P<0.05).With increasing Ca²⁺ concentration in incubating medium,intracellular Ca²⁺ fluorescence intensity of mantle cells was significantly enhanced(P<0.05).The present research indicated that mantle was main tissue on absorbing Ca²⁺ from external water;pearl cultivation strengthened calcium deposition in body of H.cumingii;calciumion concentration of 1.25-3 mmol/L in water was beneficial to Ca²⁺ deposition in mussel.Our research provided theory basis for pearl cultivation in fresh-water mussels.