Abstract: Interface is a very important factor in composite. In this paper, a reasonable theoretical model will be founded on the basis of the experimental analysis. By the axi symmetrical and three dimensional finite element method, the effects of interfacial performance on the mechanical behavior of short fiber reinforced metal matrix composites are studied systematically and deeply. The effects of interfacial characteristics on such aspects as stress transfer, modulus, stress strain curve and fracture mechanism are discussed. As a result, the change of interfacial performance will influence stress transfer, and thus change the modulus, stress strain curve and fracture mechanism of the composite. The interface controlling is a key factor in the design of composites.