The　traditional　Lamb　wave　structure　health　monitoring　imaging　method　based　on　reference　signal　is　affected　by　environmental　factors　such　as　temperature　change.　To　solve　this　problem,　considering　the　difference　in　the　scattered　fields　generated　by　the　interaction　between　ultrasonic　waves　and　defects　in　the　reverse　path,　a　Lamb　wave　imaging　method　is　proposed　in　this　paper　based　on　the　difference　signal　of　sparse　array　in　inverse　path.　Numerical　simulations　are　carried　out　to　determine　the　generation　conditions　of　difference　signal　in　inversion　path,　and　the　influences　of　the　angles　and　distances　between　the　defect　and　the　two　sensors　on　the　amplitude　of　difference　signal　in　inversion　path.　It　is　found　that　the　difference　signal　in　reverse　path　is　much　more　obvious　when　the　defect　appears　as　asymmetric　distribution　towards　the　excitation　sensor　and　receiving　sensors;　the　amplitude　of　difference　signal　in　inverse　path　is　affected　by　distance　difference　of　the　Lamb　wave　propagating　in　reverse　path　and　the　scattering　coefficient　of　the　defect.　On　this　basis,　the　effectiveness　of　the　Lamb　wave　imaging　method　based　on　the　difference　signal　in　inverse　path　is　studied　numerically　and　experimentally.　The　results　show　that　the　Lamb　wave　imaging　method　based　on　the　difference　signal　in　inversion　path　can　perfectly　eliminate　the　interference　between　direct　wave　and　the　boundary　reflection　wave,　and　the　imaging　method　can　detect　the　defect　at　different　positions　in　the　plate.　Moreover,　the　imaging　resolution　is　higher　and　the　defect　location　is　accurate.　The　research　work　provides　a　new　feasible　scheme　for　the　extensive　health　monitoring　of　plate　structure.