Abstract: Fifteen healthy piglets were distributed into three groups randomly: healthy group, spleen deficiency group, sijunzi decoction antisyndrome group, five piglets each. The study on “pharmacokinetics of syndrome differentiation” was carried out after a single oral administration of levofloxacin(20 mg/kg B.W.) in piglets. The levofloxacin concertration in plasma was detected with HPLC, calculation of pharmacokinetics parameters was performed using 3p97 PK programe, further pharmacokinetics analysis was performed using SPSS(12.0) statistic software. The datas of the drug concentration-time in the two groups of the healthy group, spleen deficiency group were fitted to a one-compartment model with first-order absorption, the counterparters of sijunzi decoction antisyndrome group were in line with a two-compartment with first-order absorption. The results indicated that the spleen deficiency condition of the piglets influenced the PK of levofloxacin; sijunzi decoction could resume the characteristics of the PK parameters in spleen deficiency condition, which also provided scientific evidence for the hypothesis of “pharmacokinetics of syndrome differentiation”, also for the better combination between the west animal medicine and Chinese traditional animal medicine.