【Objective】To study the pharmacokinetics characteristics of marbofloxacin in tilapia(Oreochromis niloticus), and provide references for rational clinical drug usage.【Method】The tilapia were divided into two groups for intramuscular (i.m.) and oral administrations, and each fish received marbofloxacin at a dosage of 10 mg·kg^-1 body mass. Water temperature was maintained at 30 ℃. The concentration of marbofloxacin in plasma was measured using high performance liquid chromatography（HPLC）combined with fluorescence detection. The plasma drug concentration-time data were analyzed by the non-compartment model of WinNonlin 6.1 software.【Result】After i.m. administration, marbofloxacin absorption and elimination were relatively faster, and it was widely distributed throughout the body. Peak time of plasma concentration (t_max) was 0.25 h, the maximum plasma concentration (ρ_max) was 4.31 μg·mL^-1, the elimination half-life (t_1/2λz) was 19.21 h, the volume of distribution was 3.94 L·kg^-1and the area under the plasma concentration-time curve (AUC) was 70.36 μg·mL^-1·h^-1. Following oral administration, marbofloxacin absorption and elimination were relatively slower, and it was widely distributed throughout the body. t_max was 4.00 h, ρ_max was 2.45 μg·mL^-1, t_1/2λz was 22.67 h, the volume of distribution was 4.27 L·kg^-1 and AUC was 76.66 μg·mL^-1·h ^-1.【Conclusion】Using 10 mg·kg^-1 marbofloxacin could effectively control susceptible micro-organisms involved in most common infections in tilapia.