To reveal the relationship between the single decoction and prescription, the surface-enhanced Raman scattering (SERS) spectroscopy of Sheng-Di-Dang-Gui decoction (SDDGD), Sheng-Di decoction (SDD) and Dang-Gui decoction (DGD) were tested and analyzed. Mainly seventeen Raman signals (538, 622, 732, 761, 835, 876, 959, 1 145, 1 245, 1 276, 1 326, 1 402, 1 456, 1 470, 1 518, 1 546 and 1 605 cm-1) in three decoctions were discussed. The characteristic Raman bands of three decoctions were tentatively assigned. Fifteen obvious Raman bands (538, 732, 761, 835, 876, 959, 1 145, 1 245, 1 276, 1 326, 1 402, 1 456, 1 470, 1 518 and 1 605 cm-1) were observed in the SERS spectroscopy of SDDGD, thirteen obvious Raman bands (538, 761, 835, 876, 959, 1 145, 1 245, 1 276, 1 326, 1 402, 1 470, 1 518 and 1 546 cm-1) were observed in the SERS spectroscopy of SDD, ten obvious Raman bands (538, 622, 732, 761, 835, 876, 959, 1 245, 1 326 and 1 402 cm-1) were observed in the SERS spectroscopy of DGD. Some Raman bands in SERS spectra of SDD and DGD were retained in the SDDGD, however some Raman bands in two kinds of decoctions never appeared in the SDDGD. And new Raman bands (1 456 and 1 605 cm-1) were generated in the SDDGD, resulted in the fact that new chemical compositions were created. Medical ingredients in the SDDGD were not the simple addition of SDD and DGD. The results showed that the SERS spectroscopy might provide a new kind of novel, effective and simple detecting method for the prescription research.