In general, the piezoelectric ceramic and polymer in a 1–3 type composite will have different deformations when subjected to an external field. How each component deforms, to a large extent, determines the performance of the composite. Based on the force equilibrium condition, an elastic model is introduced to analyze the strain profiles of these composites, and the theoretical results are in quantitative agreement with the strain profiles measured on several composites using a double beam ultradilatometer. The results obtained provide quantitative information on how various parameters in a composite affect the performance of the composite. Furthermore, a scheme is proposed for evaluating the strain profile of a 1–3 type composite under a hydrostatic pressure using a double beam dilatometer.