The interfacial behavior of functional films bonded to inhomogeneous substrates under the action of multi-fields is studied. The effect of geometric and materials of the functional films on the interface response is mainly concerned, including the interface stress, the stress intensity factors near both ends of films and the normal stress of films. In order to solve such a boundary value problem, Fourier transformation is used to achieve a governing integro-differential equation, which could further demonstrate the interface behavior. It is found that selecting films with high thermal conductivity and small length facilitates the stability of the film/substrate system. The possible damage at the ends of the film/substrate system can be alleviated by tuning effective parameters of the substrate. Designing a thick and soft bonding layer can be helpful for the safety of the film/substrate system. The results should be of significant importance for the blooming applications of functional materials, as well as the design of various film/substrate structures in engineering practice.