Abstract: In order to study the strength characteristics of ion-adsorption rare-earth ore，saturated triaxial test and unsaturated triaxial test of controlling matric suction were carried on typical ion-adsorption rare-earth remoulded ore in Long nan of Jiang xi，based on GDS unsaturated triaxial test system，the experimental research have shown that the stress-strain relation of saturated ore body are weak strain softening，cohesion of rare earth mineral particles contributed slightly to shear strength，the shear strength is mainly borne by the frictional resistance.The shear strength of unsaturated ore body has a large sensitivity with matric suction，suction strength increases nonlinearly with increase of matric suction，the stress-strain relation changes from hardening type into weak softening type，shear strength of unsaturated ore body increases，internal friction angle of matric suction decreases nonlinearly，it shows that contribution of matric suction to the shear strength of unsaturated ore body is limited.By using power function to fit the relation between matric suction and suction strength，the shear strength formula for ion-adsorption rare-earth unsaturated ore body of Long nan and effective stress formula were proposed.