High performance screen-printed PNN−PZN−PZT thick films have been successfully prepared using a new one-step co-firing method at relatively low sintering temperature, leaving out preceding binder removal and subsequent electrode-made processes. And the dependence of microstructure, densification and electrical properties on the content of sintering aids has been investigated. The specimens with 1wt% sintering aids sintered at 850°C exhibits markedly enhanced piezoelectric and dielectric properties: d33=202 pC/N, ε33T/ε0=987, tanδ=1.8%, Tc=295°C, and Pr=14.02μC/cm2. Furthermore, there is no obvious Ag diffusion into PZT thick films, indicating the favorable coherence. Such prominent properties of PZN−PNN−PZT thick films using one-step co-firing method can be applied to multilayer thick films and further MEMS device applications.