To improve the system resolution of the surface plasmons resonance,a surface plasmons resonance incentive model based on the five-layer structure was proposed which is prism base-silver-dielectric layer1-dielectric layer2-environment media. Silver film and double dielectric layers composed the composite resonance film. According to the thin film optics and waveguide theory,the effect of the double dielectric layer on the incentive mechanism and modulation characteristics of the surface plasmons resonance was discussed. Numerical simulation was conducted on the resonance spectroscopy of the double dielectric layers structure by finite element analysis method. The simulation result shows that,the full width half maximum of the double dielectric structure is about 0.1 times narrower than traditional prism surface plasmons resonance when the refractive index of analyte is same. The resolution of the double dielectric layers structure is 5.4 times higher than the traditional prism surface plasmons resonance. The ethylene glycol was adopted as the sample detected,the quality factor and sensitivity of the refractive index sensor were analyzed. The quality factor can attain 465 and the sensitivity can attain 7.2°/RIU,which demonstrates the feasibility of the sensing structure. This structure provides a theoretical reference for the design of high resolution and high quality factor sensing system.