The core wall material of gravelly soil of Nuozhadu earth rock dam under different degree of saturation conditions triaxial undrained shear test was carried out to research the stress-strain behavior of unsaturated gravelly soil. Analysis of the experimental curves shows that the deformation modulus of specimen decreases when water content increases under the same confining pressure; the strength of gravelly soil decreases when water content increases; cohesion and internal friction angle of specimen decreases linearly with increasing water content, and the value of cohesion decreases more obvious than the value of the internal friction angle.