Antiresonance　and　its　application　in　triple-quantum-dot　systems　are　studied　theoretically　using　nonequilibrium　Green＇s　function　method.　The　presence　or　absence　of　antiresonance　point　can　be　used　to　determine　whether　quantum　dot　impurity　exists　in　the　system.　For　a　tri-quantum-dot　ring,　the　conversion　between　0　and　1　for　the　conductance　can　be　realized　by　adjusting　the　energy　levels　of　quantum　dots,　which　makes　the　system　applicable　as　a　quantum　switch.　The　coupling　strength　can　be　measured　according　to　the　energy　level　of　the　antiresonance　point.　Once　the　intradot　Coulomb　interactions　are　taken　into　account,　three　new　Fano　antiresonances　emerge　in　the　conductance　spectrum.　Under　the　action　of　the　magnetic　field,　two　antiresonance　points　disappear　simultaneously.　Our　work　sheds　lights　onto　the　design　and　implementation　of　new　quantum　functional　devices　for　electronic　measurements.