Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) layers incorporating with Au nanoparticles (NPs) have been explored for fabricating the hybrid Si/organic solar cells. After incorporating with Au NPs, the power conversation efficiency (PCE) of 12.85% has been achieved, which corresponds to ~23% improvement comparing with that of the pristine one. The current density-voltage (J-V), external quantum efficiency (EQE), and capacitance-voltage (C-V) results show that the enhancement of the devices can be ascribed to the optical and electrical effects caused by Au NPs. After incorporating with Au NPs, the reflection of the device where the wavelength regime coincides with the plasmonic region of Au NPs is reduced. Meanwhile, the conductivity of the PEDOT:PSS layer and the built-in electric field (Vbi) of the devices are enhanced, and both of them are beneficial for charge separation and collection, significantly suppressing the recombination process of the devices.