At　first,　based　on　the　principle　of　least　squares,　the　back-analysis　method　of　the　average　shearing　strength　of　the　slip　zone　soils　with　multi-sections　is　discussed.　Secondly,　a　back-analysis　method　of　considering　different　slip　segments　with　different　shearing　strength　indexes　is　brought　forward　according　to　the　difference　of　the　matter　components　or　whether　eroded　by　groundwater　in　landslides.　A　practical　example　is　introduced　by　using　the　two　methods.　Meanwhile,　the　landslide　thrusts　of　a　section　calculated　by　utilizing　the　two　kinds　of　shearing　strength　indexes　are　compared　and　analyzed.　The　results　show　that　the　calculation　precision　of　the　former　is　still　comparatively　reliable　in　landslide　control　and　design　when　landslides　are　simple　and　in　small　scale.　However　the　latter　will　be　more　reasonable　and　reliable　in　control　and　design　of　large　or　medium　scale　landslides　as　well　as　complicated　ones.