Using the tight-binding linear muffin-tin orbital(TB-LMTO) method, we investigated the magnetism and its pressure dependence of Fe-Al system in some bcc superstructures. The results indicate that the magnetic moment of Fe in the ferromagnetic state decreases with increasing concentration of Al in the system and the volume-compression. As the concentration of Al in the system is in excess of about 0.5 the magnetism of the system will transform from ferromagnetism to paramagnetism. On the other hand, there are no pressure-induced magnetic phase transitions in the bcc Fe-Al alloys; this is different from that in the fcc Fe(γ-Fe) and some fcc Fe-based alloys. The results are in good agree-ment with the experimental results.