Perovskite multiferroic materials have gained great attentions in the past few years because they can show magnetoelectric coupling (MEC) effect. However, the MEC effect is weak in most multiferroic materials due to their low Curie temperature or poor magnetic/ferroelectric performance. Doping, solid solution, or formation of magnetoelectric composite is one of the effective ways to improve the MEC performance. In this chapter, (1–x) (Bi0.9Sm0.1Fe0.85Ti0.15O3)—x (0.2Co0.7Zn0.3Fe2O4–0.8BaTi0.85Zr0.15O3), x=0.5, 0.6, 0.7, 0.8, 0.9) composite ceramics were prepared by conventional solid-phase reaction method, and the influence of composition on the structure, dielectric, ferroelectric, magnetic performance as well as MEC effect was comparatively investigated. It can be concluded through experiment results that the intensity of XRD spectra of (1 − x) (Bi0.9Sm0.1Fe0.85Ti0.15O3)—x (0.2Co0.7Zn0.3Fe2O4–0.8BaTi0.85Zr0.15O3) composite ceramics varies with the composition. When x becomes larger, the grain size increases at first and then decreases, while the dielectric properties and ferroelectric properties are also greatly improved. The residual polarization intensity reaches 2.6841 μC/cm2, but the loss is the largest when x = 0.9, and the leakage current is the largest. With the increase in x, the more CoFe2O4, the stronger the magnetic properties. The composite ceramic has a certain room temperature magnetoelectric coupling performance. The domain follows the deflection, and the polarization is enhanced under the action of external magnetic field. All the hysteresis loops have certain changes, and the residual polarization increases from 1.0094 μC/cm2. The ferroelectricity is enhanced to 1.3045 μC/cm2.