Herein, we designed a novel D-type symmetric two-core photonic crystal fiber surface plasmon resonance refractive index sensor. A significant dual resonance peak phenomenon occurred in the visible and near-infrared bands when the surface plasmon resonance effect generated at the interface between two-core and metal-sensing layer in this structure is combined with different metal-sensing layers. The mutual independence of the dual resonance peaks was analyzed using the finite element method. Moreover, the effects of the spacing and diameter of air holes, the thickness of metal-sensing layers, and the radius and spacing of nanometer columns in the structure on the dual peaks were examined. Results demonstrate that after the structural parameters are optimized, double peak resonance facilitates the good sensing performance of the sensor. In the refractive index range of 1.32-1.43, the respective average sensitivities corresponding to the double resonance peaks are up to 6209.09 nm/RIU and 8390.91 nm/RIU, and the figures of merit are greater than 19.64 RIU ^-1and 27.06 RIU ^-1. These results provide a theoretical reference for the design of a photonic crystal fiber surface plasmon biosensor.