Variable-rate　tree　spraying　is　one　of　the　most　important　technique　of　precision　agriculture.　This　paper　presented　an　interactive　virtual　tree　spraying　method　based　on　particle　system,　which　gain　fine　control　flexible　through　parameters　such　as　the　emitter　position　and　pitch　angle,　atomizing　particle,　atomizing　anger　and　spray　penetration　depth.　We　proposed　a　2-hierarchy　collision　detection　algorithm　to　identify　the　leaves　with　dropping　particles,　which　speed　up　the　simulation　for　about　90%.　Then,　we　implemented　the　prototype　system　using　VC++　to　carry　out　the　precision　of　the　spray　as　needed.