Acontourtreeisagoodgraphicaltoolforrepresentingthespatialrelationsofcontourlinesandhasmanyapplicationsinmapgeneralization,mapannotation,terrainanalysis,etc.AnewmethodforgeneratingcontourtreesbyintroducingaVoronoi-basedinterioradjacencyconceptisproposedinthispaper.Theimmediateinterioradjacencysetisemployedtoidentifyallofthechildrencontoursofeachcontourwithoutcontourelevations.Ithasadvantagesoverexistingmethodssuchasthegeometricmethodandtheregiongrowingbasedmethod.