The aim of this work is to study the influence of residual stresses on the properties textured duplex stainless steel (DSS). The properties of both phases in DSS were studied using ray diffraction whilst external load was applied "in situ" to the sample. The interpretation experimental data is based on the diffraction elastic constants calculated by the model taking into account the anisotropy of the studied material. Carrying out measurements both compression and tension by using neutron diffraction, important differences in the evolution lattice strains were noticed. An elastoplastic model is used to predict the evolution of the stresses during loading and to identify critical resolved shear stresses and strain parameters of the material. The influence of the initial residual stresses on the yield stresses of phases is considered. The difference between tensile and compressive behaviour of the steel explained when the initial stresses (measured in the as received non-loaded sample by methods) are taken into account in model calculations. The yield stresses in each phase of studied steel have been experimentally determined and successfully compared with the results the elastoplastic self-consistent model.