Abstract: OBJECTIVE To establish a method for determining the plasma concentration of artesunate in rat with LC-MS/MS, and study the pharmacokinetic parameters of artesunate self-microemulsion in rat. METHODS Twelve SD rats were randomly divided into two groups, which were gavaged with a single dose of artesunate self-microemulsion and artesunate API at the concentration of 50 mg·kg^-1. Afterwards, the drug plasma concentrations were determined by LC-MS/MS with glipizide as an internal standard, and pharmacokinetic parameters were calculated as well. RESULTS The linear ranges of artesunate was from 1.0 to 1 000 ng·mL^-1 with a regression equation:A=294.74C-439.33(r=0.999 6), and the limit of quantitation was 1.0 ng·mL^-1. The intraday and inter-day variable coefficients were both <10%, which met the requirements of biological sample analyses. The C_max, t_1/2and AUC_0→t values of artesunate self-microemulsion were (421±41.6)ng·mL^-1,(1.48±0.17)h and (282±17.7)h·ng·mL^-1 while with values of (87.6±8.80)ng·mL^-1, (1.88±0.33)h and (43.3±1.74)h·ng·mL^-1for artesunate API. CONCLUSION The method for evaluating these pharmacokinetic parameters is simple and sensitive, which can be used for determining the content of artesunate in plasma. Besides, the bioavailability of artesunate self-microemulsion in rats is significantly improved after gavage administration compared to that of the artesunate API.