The invention discloses a detection 
system and a detection method of 
petroleum-type pollutants. The detection 
system comprises an emitting unit, a receiving unit, a reference unit and a 
signal processing unit. The emitting unit is used for emitting 
laser signals, and 
transmitted light signals and reflected light signals are outputted; an input terminal of the reference unit receives the 
transmitted light signals emitted from the emitting unit. An output terminal of the reference unit is connected to an input terminal of the 
signal processing unit. Reference signals outputted by the reference unit are transmitted to the 
signal receiving unit by the output terminal of the reference unit. A sample in a sample tank is excited by the reflected light signals, such that 
fluorescence signals are generated. The 
fluorescence signals are received by the receiving unit beside the sample tank, and are outputted to the 
signal processing unit by the receiving unit. The 
fluorescence signals are processed by the 
signal processing unit. The 
system and the method provided by the invention are based on 
laser-induced fluorescence detection principles. Emitted signals are modulated by using a modulation technology, such that the detection sensitivity of the system is high. With the method and the system, rapid, real-time, on-line and non-contact measuring upon 
water body petroleum-type 
pollutant fluorescence signals can be realized. The system and the method can be widely applied in 
water body environment monitoring.