In　sand-gravel　strata,　the　deformation　and　mechanical　behavior　of　soil　mass　as　well　as　tunnel　structure　are　mainly　controlled　by　excavation　disturbance　degree　and　mesoscopic　distribution　of　soil-rock-mixture　in　excavation　disturbance　area.　Considering　the　mesoscopic　structure　of　soil-rock-mixture,　a　multi-scale　analysis　approach　for　tunnel　excavation　in　sand-gravel　strata　is　proposed.　Then,　three　key　issues　of　the　method,　mainly　about　the　determination　of　core　region　and　non-core　region,　the　determination　of　rock　size　that　can　be　homogenized,　equivalent　method　of　soil-rock-mixture,　are　discussed.　The　basic　thought　of　the　multi-scale　analysis　approach　can　be　expressed　as　follows.　Firstly,　the　tunnel　excavation　model　in　sand-gravel　strata　is　divided　into　core　region　and　non-core　region.　In　core　region,　the　soil-rock-mixture　is　treated　as　the　two-phase　composite　composed　by　rock　block　and　soil,　while　in　non-core　region,　the　soil-rock-mixture　is　viewed　as　macroscopic　homogeneous　material.　On　this　basis,　the　simulation　and　analysis　of　tunnel　excavation　are　carried　out.　From　the　view　of　surrounding　rock　deformation　and　pressure,　the　results　are　compared　with　meso-analysis　model　and　macro-analysis　model　of　tunnel　excavation,　and　the　analysis　showed　that　the　simulation　results　of　multi-scale　analysis　approach　are　coincidence　with　meso-analysis　model.　More　importantly,　the　proposed　method　greatly　reduces　the　computational　work　and　modeling　work,　improved　the　computation　efficiency　observably.　©　2017,　Science　Press.　All　right　reserved.