The magnetization reversal and domain structure of a series of multilayer films SiO2/Ta/Fe20Ni80/FeMn/Fe20Ni80/Ta were investigated. In these films the thickness of the antiferromagnetic FeMn layer was varied while the thickness of Fe20Ni80 ferromagnetic layers were unchanged. Coercivity, exchange bias, and remanent magnetization along the easy and hard magnetization axes were analyzed in dependence on the thickness of antiferromagnetic layer. This set of experimental data allowed us to estimate the anisotropy constant of ferromagnetic layer Fe20Ni80 of 1500 erg/cm3 and the one of antiferromagnetic FeMn layer of 1,2·105 erg/cm3. A normal distribution of easy magnetization axes in the ferromagnetic layer with the dispersion of 13° was revealed.