It is a method of preparing hypophosphorous acid with electrodialysis. It comprises Ti-PbO2 anode, an insoluble cathode and an aqueous solution of hypophosphite anions in six-compartment electrolytic cell. The direct current, through the insoluble anode to cathode in electrical contact with the aqueous solution to generate H+, forms hypophosphorous acid solution. In this paper, the best term of different factors about the experiment was studied. The best condition was to keep the NaH2PO2 concentration between 300 and 500g/L, current value 3.0A, reaction time 12-18 h. The process is simple, low cost and highly efficient, which is a cleaner production without waste residue and waste water.