Fe/Gd multilayers were prepared by alternate vapor deposition of pure Fe and Gd at a rate of 0.01-0.03 nm/s in an ultra-high-vacuum electron-gun evaporation system. The effects of the constituent metal layer thickness on the microstructures and magnetic properties of the films were investigated by low angle X-ray diffraction, transmission electron microscopy, and vibrating sample magnetometer. The experimental results show that a transition from the polycrystalline to amorphous state in the Fe layers occurs with the decrease of Fe layer thickness in the Fe/Gd multilayers. The saturation magnetization of the multilayers reduces significantly with decreasing Fe layer thickness and increasing Gd layer thickness. A superparamagnetic behavior at room temperature is observed for the [Fe(0.6 nm)/Gd(4.0 nm)]15 multilayer due to the formation of discontinuous Fe layers. Fe / Gd multilayers were prepared by alternate vapor deposition of pure Fe and Gd at a rate of 0.01-0.03 nm / s in an ultra-high-vacuum electron-gun evaporation system. The effects of the constituent metal layer thickness on the microstructures and magnetic properties of the films were investigated by low angle X-ray diffraction, transmission electron microscopy, and vibrating sample magnetometer. The experimental results show that a transition from the polycrystalline to amorphous state in the Fe layers occurs with the decrease of Fe layer thickness in The saturation magnetization of the multilayers reduces significantly with decreasing Fe layer thickness and increasing Gd layer thickness. A superparamagnetic behavior at room temperature observed for the [Fe (0.6 nm) / Gd (4.0 nm)] 15 multilayer due to the formation of discontinuous Fe layers.