In order to obtain new hybrid improper ferroelectricity, the (1-x)Sr3Sn2O7+xCa3Mn2O7 (0 x 0.2) samples each with a Ruddlesden-Popper phase are prepared by the conventional solid-state reaction method. The phase purity is characterized by X-ray diffraction through using the GSAS refinement. The results indicate that (1-x)Sr3Sn2O7+xCa3Mn2O7 sample has an orthorhombic structure and its cell constants decrease with content x increasing. At room temperature, the dielectric constant decreases with frequency increasing. Sr3Sn2O7 exhibits diamagnetism. With increasing the content of Ca3Mn2O7, the sample presents diamagnetism, paramagnetism, weak ferromagnetic and paramagnetism in sequence. And the sample with x=0.1 has a weak ferromagnetic property. All these pave a way for selecting Ruddlesden-Popper multiferroic materials.