Abstract: Objective: To optimize the thermosensitive in situ gel system containing antofloxacin for ocular use by the central composite design-response surface methodology.Methods:The in situ thermosensitive gel system containing antofloxacin was prepared with Poloxamer 407 and Poloxamer 188.The phase transition temperature of the solution-gel before and after the STF dilution was used as index.The mathematic relation of the factors and indicators,effective surface figure and contour map were described using binomial model.The formulation was optimized and validated by superimposed contour plot.Results:Optimized formulation of in situ thermosensitive gel system containing antofloxacin for ocular use consisted of 22.5% of Poloxamer 407 and 1.0% of Poloxamer 188,which was a free-flowing liquid at room temperature and converted to firm gel after STF dilution.Conclusions:The thermosensitive in situ gel system containing antofloxacin hydrochloride satisfied the requirement of ophthalmic application,which has clinical significance and application value.