Highly (001) oriented (K,Na)NbO3 (KNN) lead-free piezoelectric thin films were grown on LaNiO3 (LNO)-coated silicon by RF magnetron sputtering. The effects of the top electrodes on the electrical properties of KNN thin films were investigated. The dielectric and piezoelectric properties were remarkably improved in LNO/KNN/LNO (epsilon(r)=899 at 1kHz, d(33)= 58pm/V), compared with that in Pt/KNN/LNO (epsilon(r)=584 at 1kHz, d(33)=26pm/V). An enhanced ferroelectricity was also obtained in LNO/KNN/LNO, with a remnant polarization of 12 mu C/cm(2) and a maximum polarization of 23 mu C/cm(2) at the applied field of 200kV/cm. Besides, the temperature dependence of piezoelectricity of the films was characterized in this study.