The β-carotene, with carbon-carbon single and double bonds (C—C, CC), is a typical linear polyenes, which widely exists in plants and has important biological function and plays an important role in investigating the π-electron conjugated properties. According to the Andreas’s study, when the exciting wavelength falls in electron absorption band, it will produce the resonance Raman effect and the Raman intensity can enhance 106 times. The Raman spectra of different parts of the carrot, white radish and green radish and the β-carotene are measured by using the resonance Raman spectroscopy, finding that the Raman spectra of carrot match well with β-carotene due to a high β-carotene content in carrots. Studies from Gellerman et al. show that the sample concentration is directly proportional to Raman peak intensity, which is clearly seen from the β-carotene Raman spectrum: the Raman intensity of three kinds of radish vertical root head to taproot and lateral skin to core gradually decrease, and the Raman intensity of C—C of the green and white radishes are lower and occur peak splitting. Calculating to intensity ratio of carbon-carbon single and double bonds to the carbon-hydrogen (C—H), the variation rates of ICC/IC—H of different measuring parts (horizontal and vertical) of three kind radish are close: the rates of change of epidermis and root core of carrot are A1=0.213 3 and A2=0.215 9, and the outside and inside of green radish are B1=0.219 1 and B2=0.211 4, and the outside and inside of white radish are D1=0.223 9 and D2=0.224 1; However, variation rates of IC—C/IC—H with the different measuring parts are greatly different: the carrot are a1=0.212 1 and a2=0.232 4, and the green radish are b1=0.263 5 and b2=0.268 7, and the white radish are d1=0.369 0 and d2=0.304 9. It is found that Raman intensity ratios of C—C to the C—H of three kinds with the different parts are greatly different, but the ratios of CC to C—H has similar distribution. This is due to the low levels of β-carotene in green and white radishes, the vibrational peak of C—C occurs peak splitting, namely, two vibrational peaks appear at 1 130 and 1 156 cm-1. As the amount of β-carotene decrease, the intensity of C—C peak reduces, and the intensity of new peak is induce, making the peak intensity of the original peak greatly reduce. This is consistent with the results of IC—C/IC—H. Therefore, using the Raman intensity of C=C to analyze the β-carotene content of different parts is more accurately. Furthermore, studies of the content of the β-carotene in different parts of radish can help to provide a good theoretical basis for daily consumption and dietary nutrition.