Analytical procedures are developed on the basis of micromechanical approaches for a composite system consisting of shape memory alloy (SMA) short fibers within an elastic matrix. The equivalent inclusion model is developed for studying the mechanical behavior of shape memory (SM) composites in which the SMA short fiber is embedded in the surrounding homogenized composite. We pay most attention to the discussion of the influences of the fiber volume fraction and fiber aspect ratio on the mechanical response and the critical stress of the phase transformation. The solution addresses the complexities induced by the nonlinear dependence of the in situ martensite volume fraction of the fibers on the local stress and temperature. The applications illustrate the mechanical response of SM composites in isothermal longitudinal loading and unloading. The phase transformation critical stresses of SM composites are also discussed under various temperatures. The numerical solutions show that the fiber volume fraction and fiber aspect ratio have a strong influence on the critical stress of the phase transformation and the mechanical response of the SM composites. These results are helpful to better understand the mechanical behavior of SM composites and to design SM composite materials.