This is to study the influences of analyte refractive index, metal film thickness, and interaction length on the behavior of waveguide-based surface plasmon resonance (SPR) sensors. To understand the basic characteristics of the device, multilayer structure with complex indices is simulated based on transfer matrix method and complex mode tracking technique. Moreover, SPR sensors using Ge-doped SiO2 optical waveguide on Si substrate, and Au as the sensing film are successfully implemented by semiconductor fabrication process. The sensitivity and SPR-induced attenuation as high as 5532.33 nm/RIU and 14.80 dB, respectively, are observed. The experimental results exhibit the same trend as predicted by the simulation.