The invention relates to a method for preparing K0.5Na0.5NbO3 superfine powder at low temperature; firstly, the powder of reactants: NB2o5, Na2CO3 and K2CO3, is mixed, and then the mixed powder is added with urea, an incendiary agent, which accounts for 80%-200% weight of the mixed powder; secondly, the mixture is put in a vessel and calcined at 550 DEG C-750 DEG C for more than 6 hours; finally, the calcined product is porphyrized to obtain the K0.5Na0.5NbO3 superfine powder. The K0.5Na0.5NbO3 powder prepared by the invention has high degree of crystallinity, fine particle size, narrow grain size distribution, little agglomeration, good uniformity, and the like; meanwhile, the adoption of urea can lower synthetic temperature; furthermore, the method of the invention has simple technical process and equipment, convenient operation, inexpensive and easily available raw materials and low preparing cost of the powder and is suitable for industrial production; therefore, the method has strong practicability.