Abstract: Spent fuel reprocessing technology must be developed accordingly to achieve the closed nuclear fuel cycle of fast reactor in order to keep sustainable development of nuclear energy. Hydrometallurgical processes still based on the PUREX process for the moment, so further studies were needed on the head-end process of spent nuclear fuel element, the simplification of extraction technology and the valence adjustment without any salt, etc. At the same time, with increasing burn up of the power reactor, the behavior and morphology of Np/Pu and other high-yield fission products in the spent fuel element such as Ru/Tc/Zr in water processing technology become increasingly significant. The problems mentioned above were elaborated in this paper and the crucial points of the research were proposed correspondingly.