Abstract: In this study, we determined the controlled-release properties of Norfloxacin (NFLX) microencapsulation which was embedded with chitosan. We approached this goal by examining the pharmacokinetic activity of NFLX in the plasma of Ctenopharyngodon idellus. The results showed that the base line was smooth and the object peak of NFLX was clearly separated from the others. The mean recovery rate of NFLX in plasma was (94.3286.231)%. The results of the precision test were satisfying. The intra-days and extra-days precision values were 1.988% and 2.648% respectively. We compared the pharmacokinetic properties of embedded and un-embedded NFLX in the plasma of Ctenopharyngodon idellus. Chitosan was a key factor that accounted for the differences between these two groups. The embedded NFLX exhibited the delayed absorption speed, distribution, and elimination in the Plasma. The T1/2 ka of embedded group was about eight times higher than that of the un-embedded group. The T1/2 and T1/2 of the embedded group were much longer too. The Tp of embedded group was more than two times higher than that of the un-embedded group. The CLs of the embedded group was about half of that of the un-embedded group. The absorption speed of the 5-time embedded group was higher than that of the 10-time embedded group. The T1/2 and AUC of the 5-time embedded group were close to that of the 10-time embedded group. However, the absorption and elimination speeds of the former group were faster than those of the latter. The pharmacokinetic differences between norfloxacin-chitosan microcapsules and norfloxacin alone in grass carp suggested that the chitosan embedding should affect the release efficacy, the absorption, and metabolism of NFLX in fish. In real production we can use chitosan as a release agent to preserve the effects of NFLX and to delay absorption and metabolism of the drug in the organism, hereby to improve its effects.