Liquid　chromatography-tandem　mass　spectrometry　(LC-MS/MS)　was　used　to　determine　three　pesticide　residues　including　carbendazim,　diethofencarb　and　prochloraz　in　four　different　processed　products　of　Agaricus　bisporus.　Meanwhile,　the　key　process　and　parameters　for　reducing　pesticide　residues　were　analyzed.　The　results　showed　that　the　percentage　removal　of　three　pesticide　residues　by　different　processing　methods　were　in　the　following　decreasing　order:　canning＞salting＞quick　freezing＞freeze　drying,　and　the　residual　levels　of　pesticides　in　these　processed　products　were　in　the　ranges　of　3.4%-11.7%,　11.5%-22.3%,　61.5%-86.1%　and　150.4%-152.3%　respectively.　Washing　and　heating　were　the　key　steps　for　reducing　3　pesticide　residues　in　canned　products.　Soaking　in　Na2CO3　solution　for　25　minutes　was　the　most　effective　among　these　processing　treatments,　resulting　in　37.2%　removal　of　carbendazim.　The　percentage　removal　of　three　pesticides　were　increased　by　increasing　precooking　time,　which　were　22.0%,　15.9%,　and　17.1%,　respectively　after　precooking　for　14　minutes.　©　2017,　China　Food　Publishing　Company.　All　right　reserved.