After NaNbO3 and KNbO3 powders were prepared respectively by the hydrothermal synthesis method, the obtained powders were mixed with the molar ratio of 1∶1, the (K, Na) NbO3 (KNN) lead free piezoelectric ceramics were obtained by sintering at 1 040 1 100 ℃ at normal atmosphere. The effect of sintering temperature on phase, microstructures, bulk density and electrical properties of KNN ceramics were investigated. The XRD patterns showed that the single solid solution of (Na,K)NbO3 ceramics was acquired. Besides, FESEM micrographs exhibited that appropriate sintering temperature would improve grain growth and increase density, thus improve the piezoelectric properties of ceramics. Samples sintered at 1 080 ℃ had the maximum bulk density of 4.46 g/cm3, and exhibited optimal performance of d33 of 96 pC/N,kp of 0.37,Qm of 108,εr of 450, tan δ of 0.024 and TC of 417 ℃.