FISH functions written were used to calculate the axial,lateral and volumetric strains as well as the Poisson's ratio of a rock specimen with a material imperfection closer to the left-upper corner in plane strain compression.Using FLAC,the effects of end-restraint(or end-constraint)on shear band pattern,entire deformational characteristics and lateral displacement distribution were investigated.In elastic and strain-softening stages,the constitutive relations were linear;a composite Mohr-Coulomb criterion with tension cut-off was used.The failure mode of rock specimen and shear band inclination are not nearly affected by end-restraint so that the post-peak slopes of stress-axial strain curve and stress-lateral strain curve do not depend on the end-restraint.Shear band propagation is faster in the specimen with smooth ends than that in the specimen with rough ends.For smooth ends,higher Poisson's ratio is found.The stress-axial strain curve,stress-lateral strain curve,lateral strain-axial strain curve and volumetric strain-axial strain curve of rock specimen with smooth ends are enveloped by those of rock specimen with rough ends.For smooth ends,the precursor to shear failure is more apparent.For different end-restraints,the lateral displacement distribution of rock specimen is non-uniform.Generally,the maximum lateral displacement of rock specimen with smooth ends is higher.The similar lateral displacement distribution is observed at higher axial strain except for the nodes near the two ends of the specimen,reflecting the similar failure mode of rock specimen with different end-restraints.