The proposed model can qualitatively describe the occurrence of high-temperature superconductivity in FeSe/SrTiO3. The Hamiltonian of a two-layer system is reduced to a twoband Hamiltonian, taking into account all possible pairing of electrons inside one energy band and electrons in the different energy bands. The superconductivity mechanism can be both phononic and electronic. The main factor is the presence of a large number of constants of the electron–electron interactions that contribute to the formation of Cooper pairs and also the possibility of increasing the ratio of densities of electronic energy bands N2/N1 by doping the systems or in some other way. A method for experimental verification of the dominance of interband interactions over intraband interactions is proposed.