The Ag-BaO photocathode with internal field-assisted structure was successfully fabricated through depositing silver electrode on the surface of Ag-BaO thin film. Photoemission enhancement was observed when the internal field-assisted bias was applied to the Ag-BaO thin film. Theoretical analysis shows that enhanced photoemission can be attributed to the decrease of interfacial barrier between Ag particles and BaO matrix, and the degradation of vacuum level at the surface.