In this paper, a new kind of magnetic tunneling junction FM1/NM/FM/I/FM is discussed theoretically. This structure ensures the high quality of the insulator layer, so it has important practical application. Based on the Slonezewski's free electron model and transferred matrix method, the relation between tunneling conductance(TC), tunneling magnetic resistance(TMR) and the thickness of NM, FM and the height of the barrier are discussed. In addition, the further discussions about the effects of the FM layer ...