Wildfire　spread　is　a　complex　process　affected　by　many　elements.　FARSITE　(Fire　Area　Simulator)　is　a　forest　fire　spread　simulation　system　widely　applied　and　recognized　in　the　world.　This　paper　briefly　describes　the　principles　of　the　forest　fire　spread　models　as　well　as　the　instruction　and　treatment　of　the　data　required　in　FARSITE.　The　three-dimensional　forest　fire　spread　simulation　system　is　then　introduced,　which　uses　the　OSG　(Open　Scene　Graph)　as　the　three-dimensional　graphic　engine,　the　particle　system　for　rendering　simulation,　and　the　FARSITE　as　the　calculation　engine.　The　three-dimensional　simulation　system　displays　the　forest　fire　spread　process　in　three　dimensions,　which　can　be　used　for　predicting　the　edge　of　the　forest　fire　and　assessing　the　lose　and　damage　as　the　burned　area,　and　contributing　to　a　more　intuitive　understanding　of　the　elements　affecting　the　forest　fire　spread.　©　Sila　Science.　All　rights　reserved.