This paper presents the principles and design of large-aperture moire deflector, with high sensitivity and high precision, which uses two methods of real-time holography to make grating for eliminating system errors. With this moire deflector some successful results were obtained including moire defiectograms of shock effect field generated by real rocket exhaust plumes and the multi-directional defiectogram of asymmetric flow, field induced in high ultrasonic speed wind tunnel.