A　simple　thermal　aptasensing　platform　was　devised　for　the　sensitive　detection　of　organophosphate　pesticides　(using　malathion　as　a　model　target)　based　on　the　efficient　self-heating　reaction　of　a　warming　pad　with　a　switchable　target　responsive　enzyme-encapsulated　three-dimensional　(3D)　DNA　hydrogel　using　a　portable　thermometer　as　a　signal　readout　in　this　work.　The　existence　of　the　target　malathion　would　open　the　catalase-3D　network　and　lots　of　catalase　was　released　from　the　hydrogel,　which　could　efficiently　convert　H2O2　to　an　O-2　molecule.　The　product　O-2　is　the　critical　condition　for　the　self-heating　of　the　warming　pad.　Thereafter,　the　temperature　was　enhanced　with　the　increasing　amount　of　O-2.　The　strategy　displays　outstanding　specificity,　reproducibility　and　stability.　Moreover,　this　method　can　be　easily　extended　to　monitor　other　molecules　using　different　aptamer　sequences　in　practical　applications.