Shear　strength　equation　is　a　basic　theory　for　solving　many　geotechnical　engineering　problems.　Although　the　shear　strength　equation　has　received　widespread　attention,　shear　strength　of　clay　under　wide　suction　range　and　different　initial　void　ratio　e$e$　conditions　cannot　be　well　predicted.　This　study　aims　to　establish　a　new　strength　equation　applicable　to　soils　within　a　wide　suction　range.　Considering　the　capillary　and　adsorptive　parts　of　soil-water　interactions,　a　cohesion　expression　related　to　the　degree　of　adsorbed　water　saturation　Sra　and　the　effective　stress　related　to　the　degree　of　capillary　water　saturation　Src　are　proposed.　After　that,　based　on　the　Mohr-Coulomb　theory,　a　shear　strength　equation　of　unsaturated　soils　in　a　wide　range　of　suction　under　various　e$e$　is　proposed.　Five　parameters　are　included　in　the　equation.　It　is　easy　to　calibrate　them　through　shear　tests　on　saturated　and　the　fully　dried　soils.　It　is　verified　that　not　only　the　sandy　clay　till　and　clayed　silt　but　also　the　expansive　soil＇s　shear　strength　in　wide　ranges　of　suction　under　various　e$e$　can　be　well　predicted.　Capillarity　and　adsorption　affect　skeleton　stress　and　cohesion,　respectively,　which　in　turn　affect　the　shear　strength.　A　strength　equation　of　soils　considering　capillarity　and　adsorption　at　various　initial　void　ratios　is　proposed.　Shear　strength　of　expansive　soil　with　various　initial　void　ratios　in　a　wide　suction　range　can　be　well　predicted.