Abstract: In order to improve U(Ⅳ) concentration and preparation rate during electrochemical process, taking 72 cm² Ru/Ir coated Ti mesh as an anode and Ti mesh as a cathode, a membrane electrolyser was set up. The performances of two different membranes were compared. The results show that the apparatus run well at a current density as high as 120 mA/cm², and the two different membranes (Nepem-417 and Aciplex-F4112) have no remarkable effect on electrolysis. After 180min electrolysis, U(Ⅳ) yield can achieve 93.1% (500 mL feed, ρ(U(Ⅵ))=199 g/L). During the electrolysis, hydrazine concentration decreases from 0.52 mol/L to 0.30 mol/L, HNO₃ concentration decreases from 2.20 mol/L to 0.70 mol/L, cell voltage varies between 3 V and 3.6 V, catholyte and anolyte temperature is below 45℃ (room temperature is 28℃).