A sensitive, simple and fast method for the detertination of Vitamin B-1 with nanoparticles as probe by resonance Reyleigh scattering (RRS) technique has been developed. In the presence of excess F copper nartoparticles were prepare(l by Using the reduction reaction of NaBH, an(I copper sulphate. In the solution, I- anions self-assemble on the surface of copper nanoparticles an(I become large anionic complexes [CunIm](x-). It can react further with Vitamin B, cations to form binging products, resulting in the change of the absorption spectrum an(I great enhancement of RRS intensity. The maximum scatting wavelength is 369 nm. There was a linear relationship between the RRS intensity(Delta I) and the Vitainin B-1 concentration in the range 40.02 -0.40 mg/L. The (letechon livint. For Vitamin B-1 was 6.4 mu g/L.