Lycopene and β-carotene are two important nutritional components in tomato. The main Raman spectrum group of lycopene and β-carotene abundant in tomato is identical and difficult to bedistinguished through fundamental frequency. With excitation wavelength of 514.5 nm, the excited light was just present in the half width range of the main absorption bands of Lycopene and β-carotene, so the resonance Raman effect can occur. Based on resonance Raman spectra, by on-body measuring the second harmonic of stretching vibration of carbon-carbon conjugated double bond in lycopene and β-carotene, the content of lycopene and β-carotene can be obtained according to the integrated intensity of each component calculated by software. And this provides a method for on-body determining the content of the components with the homologous group.