As　the　viewing　range　of　the　existing　fire　detection　devices　is　normally　short,　and　directional　detection　of　the　flame　can　not　be　achieved,　it　can　not　be　used　in　many　cases.　An　optical　design　and　implementation　based　on　flame　pyroelectric　sensor　are　present　in　this　paper.　Two　types　of　directional　flame　detection　are　provided.　One　is　to　achieve　plane-type　directional　detection,　and　the　other　is　to　achieve　line-type　directional　detection.　For　plane-type　directional　detection,　the　optical　viewing　angle　design　of　detection　device　in　the　horizontal　and　vertical　direction　is　asymmetric.　The　viewing　angle　of　vertical　direction　is　much　bigger　than　that　of　horizontal　direction　in　order　to　detect　the　flame　anywhere　in　vertical　plane　as　far　as　possible.　On　the　other　hand,　the　viewing　angle　of　horizontal　direction　is　expected　to　be　smaller　so　as　to　ensure　directional　flame　detection.　The　size　of　viewing　angle　is　controlled　within　a　certain　range　through　a　special　optical　design　including　lens　and　slit.　The　design　of　line-type　directional　detection　is　achieved　based　on　ultra-small　viewing　angle　of　the　lens.　Based　on　such　design　of　flame　detectors,　the　detection　range　can　be　adjusted　by　changing　the　optical　parameters,　so　long-distance　flame　detection　can　be　achieved.　This　scheme　has　a　broad　application　prospects　in　many　fields,　such　as　forest　fire　prevention,　automatic　fire　cannons,　etc.,　because　of　directional　flame　detection.　Experiments　show　that　this　method　has　achieved　the　expected　results.　©2010　IEEE.