The analytical approach of a plane deformation of a plate experiencing austenitemartensite transformation is developed. The thin plate is considered which energy takes into account the appearance of the martensitic transformation besides large elastic strains. The former generates specific microstrains that destroy compactness and translational order of the original perfect crystal. Making use of the previously analyzed model of a complex lattice consisting from two mutually penetrating sublattices enable us to describe both the long and the short possible destruction of the crystal order. The conservation of the polar momentum that is coupled with a mutual shift of the sublattices is taken into account. A possible cardinal reconstruction of the whole lattice and in particular the change of the number of the nearest atomic neighbours is allowed in contrast to the classical Landau theory of phase transitions. It is relaxing of the latter restriction in our theory that enables us to apply it to crystals experiencing martensitic transformations.