A simple method,immersion plating,used to make SERS-active substrate was reported.Employing AuCl₃ Sol,Au nanoparticles were overlaid on the substrate of aluminum plate. SEM image for the Au substrate shows that the shape of Au aurum is island with the average diameter of 80nm. The SERS spectra of pyridine and poly(4-vinylpyridine)molecules on Au substrate were measured. Calculation results indicate that the SERS-active Au substrate made in this way has an enhancement factor of 10⁵. And this substrate is fairly stable after being placed in air for one week.