This　study　investigated　the　variation　of　profile　curvature　accuracy　with　the　change　of　DEM　resolution,　and　proposed　the　index　of　profile　curvature　accuracy　on　the　basis　of　the　concept　of　mutual　information.　Five　major　areas　which　represent　different　geomorphology　were　chosen　as　the　sample　areas,　and　DEMs　with　resolutions　at　5,　15,　25,　35,　45,　55,　65,　and　75　m　were　established　in　terms　of　the　map　scaled　1:104.　The　profile　curvature　derived　from　DEM　at　5　m　was　assumed　as　the　true　value　to　examin　the　variation　rules　of　the　profile　curvature　derived　from　different　resolutions　of　DEMs.　The　study　results　show　that　there　exist　power　functions　between　RMSE　(root　mean　square　error)　and　the　index,　and　that　the　exponential　functions　exist　between　the　index　and　the　resolutions　of　DEM.　Besides,　the　computational　formula　for　the　resolutions　of　DEM　is　obtained　in　the　use　of　the　index.　This　formula　can　provide　the　basis　for　reducing　data　size　and　cost　as　well　as　for　choosing　proper　resolutions　of　DEM　under　the　condition　of　guaranteeing　pre-determined　accuracy　of　profile　curvature.