Abstract: The tetravalent uranium is widely used as the reduction stripping agent in many spent nuclear fuel reprocessing plants. And the preparation of tetravalent uranium plays a significant role in the nuclear fuel reprocessing technology. However, there still exist some problems in the preparation of U（Ⅳ） because of its instability. The research progress on U（Ⅳ） preparation is thus introduced in this review, which is mainly focused on the reaction progress, reaction mechanism and the effect of catalysts in the catalytic reduction of U（Ⅵ） by hydrazine in various media. Furthermore, a perspective of the preparation of U（Ⅳ） by catalytic reduction of U（Ⅵ） is presented.