Mn/Sb multilayer filmswith different thicknesses were grown on GaAs(100) and glass by ultrahigh vacuum(UHV)evaporation technique and then annealing for a short duration(1 or 20 min). Magnetizationmeasurements revealed strong room temperature ferromagnetism. And when the thickness oflayers was increased from 700 to 1600,the saturation magnetization increased nearlydouble; and the polar and longitudinal Kerr saturation angles θk increased too, but less than two times. It indicates that both themagnetization and Kerr rotation angle depend on the thickness of layers, but are notsimply proportional to the thickness of the layers. The saturation magnetization and boththe polar and longitudinal Kerr saturation angles can be enhanced with increasing thethickness of the layers. X ray diffraction(XRD) pattern results show that high qualitycrystal structures of thicker Mn/Sb films can be fabricated by UHV evaporation techniquewith subsequent thermal annealing for a very short duration(about 1 min).