This study proposes a method that involves depositing a highly reflective metal film on the dead-zone surface of the SiPM. This structure forms an optical resonant cavity with the transparent encapsulation layer, redirecting incident light from the dead zones to the photosensitive regions, thereby enhancing both the PDE and absolute quantum efficiency. The mechanism behind this enhancement was analyzed using geometric optics modeling in combination with simulations performed in Comsol Multiphysics. Theoretical calculations and optical simulations reveal an increase in light transmittance of 6.23% and 6.31%, respectively. Additionally, semiconductor device simulations demonstrate a 6.2% improvement in absolute quantum efficiency, aligning closely with the simulated transmittance gains. This approach effectively mitigates losses due to the dead zones, offering a viable solution for enhancing the photon detection capabilities of SiPMs.