With　improved　Brust　method,　we　synthesized　1-hexanthiol　modified　gold-silver　alloy　nanoparticles　with　an　atomic　composition　of　Ag0.66Au0.33.　Using　the　alloy　nanoparticles　as　＂building　block＂,　we　successfully　assemble　one-dimensional　waveguided　alloy　photonic　crystals　through　a　solution　processible　method.　Under　the　same　conditions,　the　sensitivity　of　the　biosensor　built　with　the　waveguided　alloy　photonic　crystals　is　2.5　times　as　large　as　that　of　the　similar　structure　made　of　pure　gold.　Gold-silver　alloy　nanoparticles　assembled　waveguided　metallic　photonic　crystals　exhibit　potential　application　in　biosensors　due　to　the　low-cost　fabrication　process　and　simple　testing　methods.