OBJECTIVE： To determine the concentration of cefdinir in rat plasma， and investigate its pharmacokinetics. METHODS： High performance capillary electrophoresis （HPCE） was adopted by using fused-silica capillary （75 μm， total length of 30 cm， effective length of 21.5 cm）， buffer solution of 20 mmol/L citric acid， injection voltage of 10 kV for 10 s， separation voltage of －20 kV， and detection wavelength of 214 nm. 6 rats were intragastrically received cefdinir solution （20 mg/kg）. 0.2 mL blood sample was taken from the tail vein before and 0.25， 0.5， 1， 1.5， 2， 3， 4， 6， 12， 24 h after administration. BAPP 2.0 software was used to calculate the pharmacokinetics parameters. RESULTS： The linear range of cedinir ranged 0.2-50 μg/mL （r＝0.999 7）， lower limit of quantification was 0.2 μg/mL. The intra-day （n＝6） and inter-day RSDs of （n＝3） precision test were no more than 12.2％； RSD of stability test was no more than 9.10％ （n＝6）； method recovery rate was 95.4％-114.3％ （RSD＝9.0％， n＝6）； matrix effect was 63.5％-70.2％ （RSD＝10.39％， n＝6）. The t1/2 of cefdinir in rats in vivo was （0.54±0.01） h， MRT was （1.90±0.14） h， cmax was （32.92±0.81） μg/mL， tmax was （1.50±0.02） h， AUC0-24 h was （46.65±0.44） μg·h/mL and AUC0-∞ was （46.83±0.44） μg·h/mL. CONCLUSIONS： The method is rapid， accurate and simple， and can be used for the determination of cefdinir concentration in rat plasma and its pharmacokinetics research.