Fluorescence optical fiber sensor is one of the hot-spot problems in the field of modem optical fiber sensor technology. The concentration of measured materials is decided by measuring its special fluorescence spectrum. This paper presents a novel type of fluorescence optical fiber measurement system for measuring oil concentration in seawater, which combines fluorescence spectrum processing with optical fiber sensing technique. The basic principle and characteristic of fluorescence measurement method are discussed. The fluorescence specific properties of oil in seawater are analyzed. And then the total scheme of the fluorescence optical fiber measurement system is designed. According to the comparative study of energy spectrum distribution of light source, the pulse xenon lamp with UV spectrum, which has low-power consumption, high strength, and low-repeat frequency, is used as the excitation light source. And low-loss silicon optical fiber bundle has been used as transfer channel of light signal. We also redesign the optical fiber probe to effectively eliminate light noise and make seawater exchange real time. In order to effectively separate the fluorescence produced by oil in seawater and the scatter light from the exciting light, high block coefficient, narrow band interference filters are used as spectrum filters. The detecting method of double light route and double channel at the same time is used to eliminate the signal variation due to undulation of the exciting light source. Experiments indicate that the prototype processes many advantages, such as good relativity and repeatability, high-precision, good real time, and anti-jamming. It seems that it will get wide applications foreground in the field of environment measurement.