Barium titanate (BaTiO3, BT) and potassium niobate (KNbO3, KN) (BT-KN) nano-structured ceramics with artificial morphotropic phase boundary (MPB) structure were successfully prepared by solvothermal method at temperatures below 230 ˚C. Various characterizations confirmed that the BT-KN nano-structured ceramics exhibited BT/KN molar ratio of 1, a porosity of around 30 % and heteroepitaxial interface between BT and KN. Their apparent piezoelectric constant d33* was estimated at 136 pC/N, and was three times larger value than that of the 0.5BT-0.5KN dense ceramics. The concept proposed in this study can be a new way to create piezoelectric ceramics with artificial MPB region. Moreover, this method is very universal and applied into various functional materials such as magnetic, conductive, semi-conductive, and optical materials in addition to dielectric, piezoelectric and ferroelectric materials. In the future, we will develop various new materials with heteroepitaxial interfaces on the basis of the concept.