The invention discloses a surface enhanced Raman scattering probe based on a carbon nanotube and a preparation method thereof. By adopting the structural characteristics of the carbon nanotube, the surface enhanced Raman scattering signal intensity of the probe is raised. The probe comprises a core layer, a coating layer adsorbing around the core layer and a surface enhanced Raman scattering marker adsorbing around the coating layer, wherein the core layer comprises a carbon nanotube coated with a layer of positive polypropylene amine hydrochloride, and the coating layer is a metal nanoparticle layer composing of metal nanoparticles. According to the invention, the surface enhanced Raman scattering probe with a specific structure is prepared by using the metal nanoparticles as a surface enhanced Raman scattering substrate and using the carbon nanotube as a loading template; under the irradiation of excitation lights, the probe has surface enhanced Raman scattering signals with high signal to noise ratio.