With the increasing development of polymeric materials, it becomes important for research on mechanical properties of polymeric materials under large deformation conditions. To know displacement distributions in the polymeric structures could help us to better understand the deformation characteristics of polymeric structures in fracture analysis. In this paper, an experimental digital moiré method for the in-plane deformation measurement in a sample of transparent polymeric material, which is a non-contact method for full-field, large deformation and real-time measurement, is presented. The measurement principles and the basic procedures of the method are explained in detail. In order to demonstrate this method, a cross grating is generated and put into a transparent polymeric specimen. The subsequent fringe and displacement analysis is carried out using the method developed by the authors.