[Objective] The technological conditions of preparing food additive sodium polyacrylate were discussed.[Method]Using(NH4)2S2O8-NaHSO3 as mixed initiator,the influences of monomer concentration,dosage of initiator components,reaction temperature,reaction time on the relative molecular mass of sodium polyacrylate were studied by using aqueous solution polymerization method.[Result] The optimum technological conditions of sodium polyacrylate were as follows:the reaction temperature of 40~45 ℃,the reaction time of 4 h,(NH4)2S2O8 dosage of 0.02%,NaHSO3 dosage of 0.01%,the monomer concentration of 45%.Under these conditions,the molecular mass of sodium polyacrylate was 30 000 000 ~ 35 000 000.[Conclusion] Through the detection,the prepared sodium polyacrylate can meet the requirements of food additive.It played good thickening and fresh-keeping effects when it was used in some kinds of food.