As the candidate for self-morphing elements and structures, the bending of composite beams including shape memory alloy fibers or plate is examined in terms of simple beam theory. The constitutive relation describing the internal stress/strain arising from the shape memory effect of the fibers is the key point of this design; this study provides the method of dealing with the stress and strain as the initial strain or the initial stress on the basis of the experimental evidences in literatures. This simplified method has advantages in deriving the geometry and statistics of the composite beam in explicit forms useful for designing purposes. The limit of the deflection of the composite beam is determined by the yield strength of the matrix: steel, aluminum and epoxy are considered.