Magnetic tunnel junctions (MTJs), as the core storage unit of magneto resistive random-access memory (MRAM), have received a lot of attention and have a very important position in spintronics. In the MTJ devices, magnetic/nonmagnetic heterojunction structures are included, consisting of magnetic metals and magnetic insulators or nonmagnetic metals. The interface of the heterojunction has certain physical effects that can affect the performance of MTJ devices. In the review, combined with the existing research results, the physical mechanism of magnetic/non-magnetic heterojunction interface coupling is discussed. The influence of the interface effect of the heterojunction on the performance of MTJ devices is studied, and the optimization method is proposed specifically. This work systematically summarizes the interface effect of magnetic/non-magnetic heterojunction.