In the work, the viscoplasticity of composites with a family of fibers exposed to an inhomogeneous and non-stationary temperature field was examined. The general constitutive and development equations have been postulated and with the help of the extension thermodynamics of the irreversible process the constitutive limitations prescribed by the second law of thermodynamics have been implemented. The law of yield is excluded (i.e. the rate of plastic deformation is not perpendicular to the yield surface). Especially the case of small strain rate, temperature gradient and elastic strains, then finite plastic strains has been analyzed. In addition to the mechanical anisotropy, thermal anisotropy caused by plastic deformations was also obtained.