The most widely used piezoelectric ceramics are lead oxide based ferroelectrics (PZT). However, the toxicity of lead oxide and its high vapor pressure during processing have led to a demand for alternative lead-free piezoelectric materials. We synthesized Lead-free piezoelectric ceramics of 0.96(K0.5Na0.5)NbO3-0.04SrZrO3+x mol% ZrO2 [KNN-SZ+xZrO2; x= 0～0.10] doped with 0.1 wt% MnO2 by a conventional solid state method. We investigated the piezoelectric properties and microstructures of these disk samples sintered in reduced atmosphere in order to evaluate the possibility of the multilayered piezoelectric ceramics having the base metal such as Ni as a internal electrode. All of these KNN-SZ samples sintered in 3%H2-97%N2 atmosphere at 1,140℃ exhibit pure perovskite structure irrespective of the content of ZrO2. Meanwhile, the sintering denisty and piezoelectric properties such as Kp, Qm and d33 of KNN-SZ samples as a function of ZrO2 content show the maxima (kp= 28.07%, Qm= 101.34, d33= 156 pC/N) at x= 0.04 and it is likely that there is some morphotropic phase boundary(MPB) in this KNN-SZ+xZrO2 composition system. These results indicate that the ceramic composition is a promising candidate material for applications in lead free multilayer piezoelectric ceramics.