Waveguide-plasmon　polaritons　sustained　in　metallic　photonic　crystal　slabs　show　fascinating　properties,　such　as　narrow　bandwidth　and　ultrafast　dynamics　crucial　for　biosensing,　light　emitting,　and　ultrafast　switching.　However,　the　patterning　of　metallic　photonic　crystals　using　electron　beam　lithography　is　challenging　in　terms　of　high　efficiency,　large　area　coverage,　and　cost　control.　This　paper　describes　a　controllable　patterning　technique　for　the　fabrication　of　an　Ag　grating　structure　on　an　indium-tin　oxide　(ITO)　slab　that　enables　strong　photon-plasmon　interaction　to　obtain　waveguide-plasmon　polaritons.　The　Ag　grating　consisting　of　self-assembled　silver　nanoparticles　(NPs)　exhibits　polarization-independent　properties　for　the　excitation　of　the　hybrid　waveguide-plasmon　mode.　The　Ag　NP　grating　can　also　be　annealed　at　high　temperature　to　form　a　continuous　nanoline　grating　that　supports　the　hybrid　waveguide-plasmon　mode　only　under　transverse　magnetic　(TM)　polarization.　We　tuned　the　morphology　and　the　periodicity　of　the　Ag　grating　through　the　concentration　of　silver　salt　and　the　photoresist　template,　respectively,　to　manipulate　the　strong　coupling　between　the　plasmon　and　the　waveguide　modes　of　different　orders.