The invention relates to an amorphous copper catalyst and a preparation method and application thereof. The preparation method comprises the following steps: heating copper, aluminum, and an alloy consisting of a transition metal M and aluminum to melt; rapidly cooling and curing the melts; and performing extraction treatment on the cured alloy by using alkali solution so as to extract most aluminum to obtain the catalyst. The catalyst prepared by the method has high catalytic activity and stability and excellent abrasion resistance, and can be applied to catalytic dehydrogenation oxidation reaction of diethanol amine.