In　the　Sagaut　mixed-scale　model,　an　improved　subgrid-scale　(SGS)　characteristic　length,　representing　the　scale　of　local　energy-containing　SGS　motions,　is　proposed.　Large-eddy　simulations　(LES)　at　temporal　mixing　layer　and　neutral　atmospheric　boundary　layer　indicate　that　by　the　improved　SGS　characteristic　length,　satisfactory　spatial　distribution　of　the　SGS　motions　can　be　obtained　and　are　closer　to　the　results　of　direction　numerical　simulations　(DNS).　Compared　with　the　basic　model,　the　modified　model　with　the　improved　SGS　characteristic　length　produces　more　accurate　mean　quantities　and　turbulent　statistics.　The　results　demonstrate　its　valuable　and　wide　application　to　LES.