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 sterile operation procedure， and at room temperature， their microbial limit， appearance， pH value， osmotic pressure molar concentration， 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 number 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 insoluble particle ≥10 μm and emulsion partial size increase. To garantee the safety of TPN use in the clinic， the concentration of bivalent cation in TPN prescrption should be kept in reasonable range， and TPN should be used as soon as possible after preparation.