A shape-memory polymer of polyurethane series can be designed for its glass-transition temperature T_g, beyond which a remarkable change in stiffness can occur, within the range from -30℃ to 70℃. A material containing such shape-memory polymer particles, hence, may be also designed for its macroscopic stiffness by adjusting the T_g distribution of particles. If it is so, this composite material ... [Show full abstract] then can be regarded as an intelligent material to macroscopic stiffness. In order to examine the possibility, micromechanical analysis on the macroscopic stiffness of such an intelligent material will be performed by taking into consideration of the T_g distribution of particles. Effects of temperature on the macroscopic stiffness of the material will be calculated with respect to various T_g distributions of particles. As a consequence, we can see that the macroscopic stiffness of the material is closely related with the T_g distribution of particles and, especially for the case of bimodal type of distribution, it decreases as a flight of three stairs with increase in temperature.