Based on the original optical fiber-capacitance sensor,we introduce the dissolved oxygen(DO) optical fiber sensor,which can obtain the qualitative and quantitative information of water quality simultaneously with the structure of the droplet analyzer.Based on liquid drops analysis technique(DAT),30 different concentrations of DO have been tested.Experimental results show that it is feasible to test dissolved oxygen concentration with the proposed sensor using DAT.Considering the temperature affection,the quadratic polynomial model gives the best fitting result.The system′s sensitivity is 0.1 mg/L,and the maximal relative error is 2.38%.