Abstract: In this paper, based on a phenmenological plasticity theory for orthotropicmaterial proposed by Hill, the near-tip field solution for a plane stress mode-Ⅰ stationary crack in an elastic-perfectly orthotropic plastic material is discussed in detail. There is not any discontinuous line of stress and solutions are not unique for problem of plane stress stationary crack in an elastoplastic medium with pastic orthortopy. It is found that the order of singularity of the stresses and strains in the vicinity of th...