Objective To study the pharmacokinetics of prostaglandin (PGE1) freeze-dried lipid microspheres in beagle dogs and provide reference for its clin. usage. Methods Twenty-four beagle dogs were divided randomly into the control group, low-dose group, medium-dose group and high-dose group, six in each group. Dogs were injected i.v. with reference preparation "Kaishi" and PGE1 freeze-dried lipid microspheres with 20, 32 and 64 μg/dog, resp. The blood samples were collected at different time points. LC-MS/MS method was used to detect the plasma concentration of PGE1 in beagle dogs. Results After i.v. injection at a dose of 32 μg/dog, t1/2 of PGE1 in plasma was (7.5±3.7) min, tmax was (7.6±2.9) min, Cmax was (105.0±40.4) ng/L, and AUC(0-18min) was (933.1±359.0) ng·min/L, which had no difference from those of the reference formulation (P>0.05). AUC(0-18min) and Cmax were pos. correlated with different dose levels. Besides, the pharmacokinetic result showed there were no significant statistical difference between the sexes (P>0.05). Conclusion PGE1 freeze-dried lipid microspheres have similar pharmacokinetic characteristics in comparison with the reference formulation, and different doses do not affect PGE1 pharmacokinetic profile in beagle dogs.