A supported NiB/SiO2 amorphous catalyst was prepared by impregnation and chemical reduction by KBH4. Its amorphous characteristics were determined by XRD and DSC methods. Its catalytic activity was measured during the selective hydrogenation of olefins in reformate oils. This new amorphous catalyst exhibits superior catalytic properties to the traditional post-hydrogenation catalyst, such as sulfide CoMo/Al2O3. However, significant deactivation of the catalyst was observed after reaction for 580 h. The structure of the used catalysts was determined using XRD, TEM, TG and XPS methods. Experimental results show that the deactivation is mainly caused by the surface oxidation of the active component, crystallite aggregation and carboneous species deposition.