In this paper, the composition of an on-line near infrared spectral analysis system, the development of the technique and its application in food processing, agriculture, classification of demolition waste, petrochemical industry, pharmacy and medicine are presented. The near infrared spectral analysis technique can be used to simultaneously analyze multicomponent samples without the pretreatment of samples. Because of the use with optical fiber, it has been used widely in process analysis. The on-line near infrared spectral analysis technique has a trend to customization and miniaturization.