This study was to investigate the in vitro pharmacodynamic effect of thiamphenicol( TAP) in serum of Carassius auratus on Aeromonas hydrophila. By combining the in vivo pharmacokinetics and in vitro pharmacodynamics,the pharmacodynamic effect of TAP on Aeromonas hydrophila was studied,and the data were processed and analyzed by software Excel 2007,Kinetica3P97 and Kinetica4. 4. The results showed that oral administration of singly 30 mg /kg TAP assumed a rapid assimilation-quickly peaking-slowly dispelling trend in Carassius auratus. The related parameters were measured as follows: time of peaked plasma concentration of TAP( Tpeak) of 1.5 h,peak concentration( Cmax) of 37.172 μg/mL and absorption rate( ka) of 1.523 h,half-life period T1/2( ka) of 0.455 h,lag time( TL)of 0. 02 h,elimination half life T1/2( ke) of 16.712 h. The half maximal effective concentration( EC50) was 14.28 h. The PK-PD parameters were 32.41 h in AUC0- 24/ MICserumand 23. 23 in Cmax/MICserum. Employing an inhibitory Sigmoid Emax model,the administration dosage of TAP for preventing Aeromonas hydrophila-caused bacterial septicemia was 8. 61- 46. 20 mg /kg in clinical application. Based on these,we proposed the optimal administration route for preventing and controlling the Aeromonas hydrophila-caused bacterial septicemia: delivering TAP at the ratio of 46. 20 mg /kg on diseased Carassius auratus by mixing with baits or oral administration,followed by delivering with baits at ratio of 8. 61 mg /kg for preventing the Aeromonas hydrophila-caused bacterial septicemia. The results provided references for applying thiamphenicol for preventing and controlling the bacterial septicemia in aquatic livestock. This combining was in vitro pharmacodynamic effect of thiamphenicol (TAP) in serum of Carassius auratus on Aeromonas hydrophila. By combining the in vivo pharmacokinetics and in vitro pharmacodynamics, the pharmacodynamic effect of TAP on Aeromonas hydrophila was studied, and the data were processed and analyzed by software Excel 2007, Kinetica 3P97 and Kinetica 4. 4. The results was that oral administration of singly 30 mg / kg TAP assumed a rapid assimilation-quickly peaking-slowly dispelling trend in Carassius auratus. The related parameters were measured as follows: time of peaked plasma concentration of TAP (Tpeak) of 1.5 h, peak concentration (Cmax) of 37.172 μg / mL and absorption rate (ka) of 1.523 h, half-life period T1 / 2 The half maximal effective concentration (EC50) was 14.28 h. The PK-PD parameters were 32.41 h in AUC0-24 / MICserumand 23 (TL) of 0. 02 h, elimination half life T1 / 2 (ke) of 16.712 h. 23 in Cmax / MICserum. Employing an inhibit ory Sigmoid Emax model, the administration dosage of TAP for balanced Aeromonas hydrophila-caused bacterial septicemia was 8. 61- 46. 20 mg / kg in clinical application. Based on these, we proposed the optimal administration route for preventing and controlling the Aeromonas hydrophila -caused bacterial septicemia: delivering TAP at the ratio of 46. 20 mg / kg on diseased Carassius auratus by mixing with baits or oral administration, followed by delivering with baits at ratio of 8. 61 mg / kg for preventing the Aeromonas hydrophila-caused bacterial results. The results provided references for applying thiamphenicol for preventing and controlling the bacterial septicemia in aquatic livestock.