Abstract: In order to get the optical dispersion specificity of different edible oils，the change characteristics of

its refractive index with the wavelength must be studied. After ignoring the scattering effect of light，a new doublelayer

slide model for the spectrophotometer has been established，the slide is used to hold the rapeseed oil，sesame

oil，kitchen waste oil，adulterated rapeseed oil，adulterated sesame oil，respectively，the transmission spectrum of

380～1500 nm is obtained experimentally. Further，the change characteristics of the refractive index in the above

five oil products with the wavelength are studied. The results have shown that the refractive index of five oil products

is more similar with the change characteristics of wavelength，and the characteristic peaks of refractive index are all

appeared at 1210 nm and 1400 nm wavelength; the refractive index of each oil product is significantly different at

its characteristic peak，the refractive index of five oil products at the wavelength of 1210 nm is 1. 512，1. 472，

1.456，1.576 and 1.612，respectively. This study has confirmed that the new double-layer slide model is feasible，

the common refractive index characteristic value and the common characteristic spectrum have indicated that there

are many related components in the different oil products. The refractive index characteristic value of five oil products

at the wavelength of 1210 nm can be used as an effective index for the identification of oil products.

Key words: food inspection, refractive index, edible oil, spectrophotometer, double-layer slide model