The optical fiber drop sensor is a type of the liquid-testing sensors based on the relationship between the dripping process and the characters of the liquid to be tested. This type of sensors can monitor the variety of the light intensity during the dripping process. The fiber fingerprint drop trace, shortly FFDT, can be gotten through analyzing the dripping process. It reflects the physical and chemical characters of liquid samples. Analyzing the fingerprint drop trace, some interrelated information can be obtained to discriminate some different liquids.Firstly, the fiber fingerprint drop trace is introduced with the corresponding characters of its every parts. Secondly, some analysis methods existing presently are summed up. At the last, two new analysis methods, the cross correlative function method and the peak of cross power spectral density function method, are put forward. These two methods are based on the correlation between the FFDTs in time region and spectral region respectively. The FFDTs of ethanol solutions and sugar solutions of different concentrations are analyzed with the correlation methods, some useful rules are obtained. Some liquid samples were tested based on these methods accurately.
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