Abstract:The detecting laser induced fluorescence spectrum system , measuring principle and method are introduced. The system is comprised of a third harmonic Nd∶YAGlaser , a spectrum instrument , an intensified CCD and a computer. The fluorescence spectrums of five species of pesticide leftover are measured Practically. The system has advantages of simple , convenient , quick , exactitude , sensitive , etc. It is fit for the detection of the pesticide leftover in the future.