Surface-enhanced Raman scattering (SERS) largely compensates for the shortcoming of the weak intensity of Raman scattering and quickly becomes a research hotspot for researchers. It is widely used in food safety, environmental pollution, drug and explosive detection and other fields. Due to nanotechnology’s development, the current research on SERS mainly focuses on the preparation of metal nanoparticle substrates. The type, size, and morphology of metal nanoparticles all affect the SERS enhancement and absorption peak positions. It is necessary to optimize the process of metal nanostructures. In particular, it is necessary to combine the structure of the metal nanoparticle and its corresponding excitation light wavelength to obtain a better enhancement effect. A study of metal nanoparticles with double resonance absorption peaks was conducted to get the relationship between SERS enhancement and absorption peaks. Firstly, through FDTD Solutions, the local surface plasmon resonance peaks of gold nanoparticles with different diameters, gold nanorods with different aspect ratios and distributions were simulated. We found that when Au nanoparticles’ theoretical diameter is about 50 nm and the theoretical aspect ratio of Au nanorods is about 3.5~4.5, the absorption peaks are distributed near 532 and 785 nm, respectively, which meets the multi-band excitation light Raman enhancement conditions. For the polarization direction of the excitation light, when the light polarization direction is along the long axis direction of Au nanorods, the absorption peak is near 785 nm, and when the light polarization direction is along the short axis of Au nanorods, the absorption peak is near 532 nm. A double-absorption SERS substrate that can be used for excitation light of various wavelengths was prepared by the seed growth method. In order to control the forming rate of Au nanorods, the process parameters were optimized, including the silver nitrate(5, 10, 20, 30, 40 μL), the hydrochloric acid (0.1, 0.2 mL) and the growth time (15, 17, 21, 23 h). Double-absorption resonance peaks containing Au nanoparticles and Au nanorods were successfully obtained. Finally, using this sample as the substrate and Rhodamine 6G(R6G) as the probe molecule, the SERS characterization of the excitation light at 532, 633 and 785 nm was tested, achieving the multiple wavelength SERS detection with a concentration of 10-7 mol·L-1 of R6G, and the enhancement factor is ~105.