A phase-shifting moiré method based on the techniques of water transfer printing grating and digital image processing was proposed for measuring the large deformation of superelastic materials such as polyurethane. Gratings were bonded onto the surfaces of a specimen and a reference object using the water transfer printing technique, and digital phase-shifting moiré fringe patterns were obtained by subtracting the specimen image from the reference grating images. The phase related to in-plane deformation was extracted from the phase-shifting moiré fringe patterns using the Carré algorithm. By using only one specimen grating image and one reference grating image to automatically yield deformation information with high accuracy, the proposed method could be used for dynamic deformation measurements with low cost, high efficiency, and high accuracy. Experiments were performed to quantitatively determine the deformation of polyurethane hoops under compression and study the mechanical response of a polyurethane bar under impact loading. Results demonstrate the validity of the proposed method.