In-situ-formed CuO nanoparticles were used to improve the interfacial mechanical properties between lead zirconate titanate (PZT) ceramic and metallization layer. The effects of CuO particles on the mechanical properties of PZT/Ag interfaces were studied, and the damage evolutions of the PZT-CuO/Ag interfaces were analyzed. The results showed that both the maximum peeling stress σmax and shear stress τmax of the PZT-CuO/Ag interfaces increased by approximately 200 %, while the critical fracture energy GIC of the interface was increased at most by seven times. The enhanced mechanical properties of the PZT-CuO/Ag interfaces originated from the high bonding strength between CuO and Ag layer and the effective stress concentration relief. Crack deflection and crack pinning effects promoted the enhancement of interfacial fracture toughness. The optimal size of the CuO particles at the PZT/Ag interface was approximately 100 nm. Notably, the electron transport between the PZT ceramic and Ag layer was not degraded with the introduction of CuO nanoparticles.