In this work, we study surface enhanced Raman spectroscopy (SERS) active substrates for the detection of Rhodamine 6G. To examine the electromagnetic enhancement, with different shape of nanoparticle, we apply the finite-difference timedomain (FDTD) algorithm to analyze the structures by solving a set of coupled Maxwell's equations in differential form. The field enhancements are investigated in the visible regime with the wavelength of 633 nm. In the experimental measurement, the surface enhanced Raman scattering signals from the surface of substrates with 12-hour hydrothermal treatment and without treatment are performed and compared. Through the three-dimensional (3D) FDTD calculation, the enhancements with different shape of nanoparticle are tested and obtained which are nanoparticle, gold nanocage and gold/silver alloy for spherical, cubic and pyramidical shapes. The results show that the enhancement of spherical and cubic shapes can be much improved by nanocage and gold/siliver alloy structures.