This paper investigates the effect of Dresselhaus spin-orbit coupling on the spin-transport properties of ferro-magnet/insulator/semiconductor/iusulator/ferromagnet double-barrier structures. The influence of the thickness of the insulator between the ferromagnct and the semiconductor on the polarization is also considered. The obtained results indicate that (I) the polarization can be enhanced by reducing the insulator layers at zero temperature, and (ii) the tunnelling magnctoresistance inversion can be illustrated by the influence of the Dresselhaus spin-orbit coupling effect in the double-barrier structure. Due to the Dresselhaus spin-orbit coupling effect, the tunnelling magnetoresistance inversion occurs when the energy of a localized state in the barrier matches the Fermi energy EF of the ferromagnetic electrodes.