The experimental observation and analysis for the influence of clamping effect on the magnetoelectric properties of the bilayer La0.7Sr0.3MnO3/BaTiO3 (LSMO/BTO) and trilayer LSMO/BTO/LSMO heterostructures were reported. Because the significant two-dimensional clamping effect caused by the lattice mismatch of the constituting layers, the relative dielectric constant and the ferroelectric coercive field of the trilayer heterostructure was lower than that of the bilayer one. Furthermore, the variation in ME voltage coefficient (alpha(E)) as a function of frequency for the two heterostructures was found to exhibit a monotonous increasing tendency. The value of alpha(E) for the trilayer heterostructure was little lower than that of the bilayer one, that is because the clamping effect suppressed both the ferroelectric properties of BTO and the transferred strain at the hetero interface.