OBJECTIVE:To study the effects of calcium ion(Ca2+)on the stability of total parenteral nutrition(TPN),and to provide reference for clinical use. METHODS:4 kinds of TPN containing different contents of Ca2+were prepared according to ster-ile operation procedure,and at room temperature,their microbial limit,appearance,pH value,osmotic pressure molar concentra-tion,the number of insoluble particle and emulsion particle size were investigated at 0,2,4,6,8 and 24 h. RESULTS:Within 24 h,no bacterial colony was found in TPN,and its appearance had no obvious change;pH value of TPN were all higher than 5 at different time points,without statistical significance(P>0.05);osmotic pressure molar concentration of TPN were all within the range of normal human blood(280-310 mOsmol/kg),without statistical significance(P>0.05). As the increase of Ca2+,the num-ber of insoluble particle ≥10 μm in TPN showed increasing tendency,with statistical significance (P<0.05);that ≥25 μm had no significant change,without statistical significance (P>0.05). There was statistical significance in emulsion partial size of TPN at different time points(P<0.05). CONCLUSIONS:Ca2+ can influence the stability of TPN,manifesting as the number of insolu-ble particle ≥10 μm and emulsion partial size increase. To garantee the safety of TPN use in the clinic,the concentration of biva-lent cation in TPN prescrption should be kept in reasonable range,and TPN should be used as soon as possible after preparation.