On-site　monitoring　the　plantation　of　genetically　modified　(GM)　crops　is　of　critical　importance　in　agriculture　industry　throughout　the　world.　In　this　paper,　a　simple,　visual　and　instrument-free　method　for　instant　on-site　detection　of　GTS　40-3-2　soybean　has　been　developed.　It　is　based　on　body-heat　recombinase　polymerase　amplification　(RPA)　and　followed　with　naked-eye　detection　via　fluorescent　DNA　dye.　Combining　with　extremely　simplified　sample　preparation,　the　whole　detection　process　can　be　accomplished　within　10　min　and　the　fluorescent　results　can　be　photographed　by　an　accompanied　smart　phone.　Results　demonstrated　a　100%　detection　rate　for　screening　of　practical　GTS　40-3-2　soybean　samples　by　20　volunteers　under　different　ambient　temperatures.　This　method　is　not　only　suitable　for　on-site　detection　of　GM　crops　but　also　demonstrates　great　potential　to　be　applied　in　other　fields.　©　2017　American　Chemical　Society.