Abstract: Dry reprocessing technology is an important development direction of nuclear fuel cycle system in China, among which the promising molten salt electrolysis requires accurate monitoring of elements in the process of industrialization to ensure safety operation. The traditional offline detection methods have complicated procedures and delay data analysis, while online monitoring technology can obtain real-time data, which attracts much attention. In this paper, the online monitoring technology of different elements in molten salt electrolysis at home and abroad in recent years is summarized. The principle, characteristics and application prospect of the cyclic voltammetry, chronoamperometry, pulse voltammetry in electroanalytical methods and fluorescence spectroscopy, UV-vis absorption spectroscopy in spectroscopic techniques were investigated and analyzed. It is expected to provide theoretical support and technical reference for the development and practical application of online monitoring technology in molten salt electrolysis.