Dielectric　elastomers　(DE)　are　emerging　electroactive　polymer　used　in　high　performance　applications　such　as　actuators　and　sensors　for　its　electromechanical　coupling　performance,　DE　can　generate　large　mechanical　deformation　under　electrical　stimulation,　the　acrylic　3M　VHB4910　series　are　most　popular　DEs.　The　electrical　parameter　of　the　material,　e.　g.　dielectric　constant,　is　key　parameter　which　determines　its　electromechanical　coupling　application.　However,　so　far　by　our　knowledge,　there　is　still　some　controversy　over　the　dielectric　constant　of　VHB4910;　especially　its　relevance　to　the　frequency,　what　is　more　there　is　not　a　very　good　theoretical　mechanism　analysis.　In　this　paper,　using　the　Broad　Band　Dielectric　Spectrometer　(BDS),　we　present　an　experimental　study　relating　to　variation　in　the　dielectric　constant　of　VHB　4910　over　wide　frequency　band　(10　-2~　to　10　7　Hz).　The　results　demonstrated　that　dielectric　constant　of　VHB4910　has　a　weak　dependence　of　low　frequency　and　become　much　more　relevant　on　high　frequency,　the　value　of　the　dielectric　constant　in　low　frequency　is　4.8.　Then　from　the　microcosmic　view,　the　mechanisms　of　orientation　polarization　polarizability　explain　the　behavior　in　frequency　of　this　parameter.　After　that,　the　characteristic　of　Debye　and　Cole　-　Cole　equation　was　analyzed.　Compared　to　the　experimental　results,　Cole　-　Cole　equation　was　more　suitable　to　describe　the　mechanism　of　the　dielectric　properties　of　VHB4910.　Finally,　the　mathematical　model　of　dielectric　properties　of　VHB4910　was　obtained　from　the　fitted　result　by　Cole　-　Cole　model.