Abstract: The Functionally Graded Shape Memory Alloy (FG-SMA) is a new kind of functionally graded composite which possesses the excellent properties of both functionally graded materials and Shape Memory Alloys (SMA). Based on the theory of micromechanics, a constitutive model for this new material is established, considering the microstructure of the material. This model can describe the mechanical behavior of the FG-SMA under complex loads accurately. With this model, a FG-SMA beam composed by elastic material and SMA subjected to an axial force and a bending moment is investigated in detail. It can be concluded from the numerical results that FG-SMA can decrease the maximum stress efficiently, preventing the destruction caused by oversize stress. Several other particular features of this new material are also observed, which will content many special requirements in practice applications. This research can provide a base for the in-depth investigation of FG-SMA material.