In　this　paper,　a　meshless　numerical　scheme,　based　on　the　generalized　finite　difference　method　(GFDM),　is　proposed　to　efficiently　and　accurately　simulate　the　sloshing　phenomenon　in　a　two-dimensional　numerical　wave　tank.　When　a　numerical　wave　tank　is　excited　horizontally　or　vertically,　the　disturbance　on　the　free　surface　and　the　flow　field　in　the　tank　is　called　sloshing.　Based　on　the　theorem　of　ideal　fluid,　the　mathematical　description　of　the　sloshing　problem　is　a　time-dependent　boundary　value　problem,　governed　by　a　second-order　partial　differential　equation　and　two　non-linear　free-surface　boundary　conditions.　In　this　paper,　the　GFDM　and　the　explicit　Euler　method　are　adopted,　respectively,　for　spatial　and　temporal　discretizations　of　this　moving-boundary　problem.　After　the　discretization　by　the　explicit　Euler　method,　the　elevation　of　free　surface　is　updated　and　a　boundary　value　problem　is　yielded　at　every　time　step.　Since　the　GFDM,　a　newly-developed　domain-type　meshless　method,　can　truly　get　rid　of　time-consuming　meshing　generation　and　numerical　quadrature,　we　adopted　the　GFDM　to　efficiently　analyze　this　boundary　value　problem　at　every　time　step.　To　use　the　moving-least　squares　method　of　the　GFDM　can　express　the　derivatives　as　linear　combinations　of　nearby　function　values,　such　that　the　numerical　procedures　of　the　GFDM　are　very　simple　and　efficient.　We　provided　four　numerical　examples　to　verify　the　simplicity　and　the　accuracy　of　the　proposed　meshless　scheme.　In　addition,　some　factors　of　the　proposed　numerical　scheme　are　systematically　investigated　via　a　series　of　numerical　experiments.　(C)　2015　Elsevier　Ltd.　All　rights　reserved.