A new technique in surface enhanced Raman spectra(SERS) study on single walled carbon nanotubes(SWCNTs) was reported.According to the remarkable mechanical property of carbon nanotubes,we whetted SWCNTs on silver foil directly.Thus rough silver surface was obtained,at the same time,the SWCNTs attached to the rough silver.High quality SERS was obtained from the area where the roughness of the silver and the thickness of the SWCNTs were well suitable.Because the disturbance of the solvent was eliminated completely,the accuracy of the result is ensured.The theory and experiment results indicate that this method is exactitude and practicable.