In this study, Pb(Zr0.52Ti0.48)O3/LaNiO3/Pb(Zr0.52Ti0.48)O3 (PZT/LNO/PZT) composite films with different LNO thicknesses were prepared by a sol-gel method. The influences of LNO interlayer on crystalline structure, microstructure and electrical properties of PZT/LNO/PZT composite films were studied. The results show that the perovskite grains of the upper PZT layer grow along the epitaxy of the LNO interlayer when the LNO layer is inserted into the composite films. Due to the in-plane compressive strain effect in the upper PZT layer and the reduced leakage current caused by the accumulated space charges at the PZT/LNO interface, an obvious enhancement of electrical properties is observed in PZT/LNO/PZT composite films. The PZT/LNO/PZT composite film with the 140-nm-thick-LNO layer possesses the best remnant polarization and dielectric constant, which are 43.3 μC cm−2 and 1841, respectively. The preparation of ferroelectric composite film with a ferroelectric/metallic oxide/ferroelectric structure provides a promising way for improving the electrical properties of ferroelectric materials.