Lead-free (1-x) Bi1/2Na1/2TiO3-xKNbO3 (x=0, 0.01, 0.02, 0.04, 0.05 0.06, 0.10) piezoelectric ceramics were prepared by conventional ceramics fabrication technique. The results of x-ray diffraction (XRD) show that these ceramics possess pure perovskite structures with a symmetry transition from rhombohedral to cubic at about x = 0.05. The piezoelectric properties of these ceramics were reported and found to reach extreme values at x = 0.04 with d33 up to 113pC/N and kp up to 22%. The temperature dependence of dielectric constant and dielectric loss of these ceramics were also investigated. The Curie temperature and depolarization temperature dropped with the increase of KNbO3 amount.