Two types of micromechanics models for CTE-mismatch superplasticity have been proposed independently. They are developed about metal matrix composites and monolithic polycrystals. The present study compares and unifies these two models. Using a newly proposed geometrical factor, similar constitutive equations at low and high applied stresses are derived quantitatively. The unified model can be applicable to explain the CTE-mismatch superplastic behavior in any metal matrix composites and monolithic polycrystals.