The properties of strain localization for elastic-plastic porous media with transversely isotro- pic elasticity under undrained conditions are investigated. Under non-associated plasticity and tri-axial stress states, the conditions for strain localization of elastic-plastic porous me- dia are derived, in which the effects of deviation from isotropic elasticity and pore fluid compressibility are included. Based on the Mohr-Coulomb yield criterion, the influences of the deviation from isotropic elasticity and pore fluid compressibility on the direction angle of localized band initiation and the corresponding critical hardening modulus for the case of plane strain are discussed. As a result, the properties of strain localization are dependent upon the deviation from isotropic elasticity and pore fluid compressibility. The deviation from isotropic elasticity and pore fluid compressibility has significant impacts on the direc- tion angle of localized band initiation and the corresponding critical hardening modulus.