The quirnary PNN-PSN-PMN-PZT piezoelectric ceramics were synthesized by the traditional solid-state process. The phase structures of these ceramics with different Zr/Ti ratio were characterized by XRD. And the effect of Zr/Ti ratio and Sr doping on the dielectric and piezoelectric properties of PNN-PSN-PMN-PZT ceramics were investigated in detail. The results indicated that the phase structure of the components was a single perovskite structure. The structure gradually transformed from the rhombohedral phase to the tetragonal phase with the Zr/Ti ratio increasing and the morphotropic phase boundary (MPB) was located at around 0.98 of Zr/Ti ratio. With the content of Sr increasing, the dielectric and piezoelectric properties of MPB compostions with Zr/Ti ratio of 0.98 increased firstly and then decreased. The specimen with 4.0%mol of Sr doping showed thetypical dielectric relaxation characteristic, andthe optimal dielectric and piezoelectric properties with the dielectric constantεT33/ε0 of 3 578, the piezoelectric constant d33 of 652 pC/N, the electromechanical coupling factor kp of 0.81, the mechanical quality factorQm of 65, the loss tangent tan δ of 1.72%, the Curie temperatureTC of 191 ℃.