The　natural　degradation　of　pyrethroids　pesticides　(bifenthrin　and　cyhalothrin)　and　benzoylurea　pesticides　(teflubenzuron,　flufenoxuron　and　chlorfluazuron)　in　the　leaves　of　Oolong　tea　trees　and　the　effect　of　processing　steps　and　pesticide＇s　dose　on　the　residue　of　above　five　pesticides　in　dried　Oolong　tea　leaf　samples　were　studied　in　detail　by　farm　experiment　and　gas　chromatography-mass　spectrometry.　The　experimental　results　showed　that:　1)　Higher　pesticide＇s　dose　used　in　tea　planting　will　result　in　higher　residue　of　pesticides　in　dried　Oolong　tea　leaf　samples,　but　the　dose　did　not　affect　the　degradation　rate　of　pesticide.　2)　The　degradation　of　bifenthrin,　cyhalothrin,　teflubenzuron,　flufenoxuron　and　chlorfluazuron　in　the　leaves　of　tea　trees　follows　zero-order　kinetics　with　a　half-life　of　9.3-9.4,　10.2-10.4,　9.2-9.6,　12.1　-13.5　and　7.0-8.2　days　respectively,　suggested　that　the　pesticide＇s　dose　and　the　interval　between　tea　picking　and　pesticide　spraying　are　two　key　factors　on　the　residue　of　fluorine-containing　pesticides　in　dried　Oolong　tea　leaf　samples.　3)　In　comparison　with　bifenthrin,　cyhalothrin,　teflubenzuron　and　flufenoxuron,　chlorfluazuron　is　more　difficult　to　be　remained　in　dried　Oolong　tea　leaf　samples.　4)　The　pesticide　residue　was　not　affected　by　the　processing　steps　except　the　fermentation　step　in　which　the　benzoylurea　insecticides　and　bifentrin　were　partially　lost　or　degraded.　The　results　of　this　study　are　helpful　for　farmer　to　safely　use　fluorine-containing　pesticides　in　Oolong　tea　planting.　(C)　2011　Elsevier　Ltd.　All　rights　reserved.