With the increase of food additives,food safety and its monitoring ha ve become an important issue related to human health.Absorption spectroscopy can qualitatively analyze substances and i dentify them.Furthermore,combined with the Lambert′s law,the concentration information can be obtained through th e relationship between absorbance and sample concentration.In this paper,qualitative and quantitative detection meth ods for food additives,such as sodium benzoate,are proposed based on absorption spectroscopy.The samples are natural beverages and beverages with pigment and preservatives.The absorption spectra in ultraviolet and visible ran ge for these samples are measured.The characteristic spectra of synthetic pigment and common preservatives,including s odium benzoate,potassium sorbate, sodium citrate and sodium carboxymethyl cellulose(CMC),are obtained and an alyzed.The results show that the peak absorption wavelengths of sodium benzoate and potassium sorbate are 252.9nm and 294.38nm,respectively. Furthermore,the absorbances of sodium benzoate under different concentrations a re measured by the monochromatic light with wavelength at 252.9nm.The relationship between absorbance and c oncentration is established.In summary,absorption spectroscopy,as an optical qualitative and quantitative analysis method, which is a non-contact measurement method,provides a new way for real- time monitoring of food.