In　order　to　investigate　the　effect　of　stress　paths　and　intermediate　principal　stress　coefficient　onthe　relation　curves　between　q-e1,　q/p-e1　and　strength　index　j　of　sand,　a　series　of　true　triaxial　drained　shear　tests　were　conducted　on　Fujian　standard　sand.　The　strength　envelope　on　the　plane　of　π　of　nonlinear　unified　strength　model　of　geo-materials　was　verified　by　the　friction　angle　and　the　measured　strength　value.　The　friction　angle　was　tested　by　the　experiments　of　triaxial　tension　and　compression,　while　the　strength　value　was　obtained　in　the　cases　of　different　intermediate　principal　stresses.　The　results　show　that　when　the　stress　path　is　exactly　the　same,　the　shearing　strength　parameters　q　and　stress　ratio　q/p　of　sand　decreases,　but　intensity　index　increases　with　increasing　of　intermediate　principal　stress　coefficient.　The　bigger　the　intermediate　principal　stress　coefficient　the　more　obvious　the　shear　dilatancy　of　sand.　Different　stress　paths　in　triaxial　shear　test　of　sand　havegreat　influence　on　the　shearing　strength　q,　but　for　strength　index　and　stress　ratio　q/p.　The　nonlinear　strength　property　of　sand　can　be　described　very　well　by　the　nonlinear　unified　strength　model　of　geo-materials.　©,　2015,　Shuili　Xuebao/Journal　of　Hydraulic　Engineering.　All　right　reserved.