The proposed transmissive display dual-screen deflectometric system solves the challenging problem that traditional methods fail to obtain the three-dimensional (3D) shape of a mirror object with a discontinuous surface. The usage of a transparent display screen not only widens the measurement field of view but also reduces the complexity of the system structure. However, the refraction effect of the transparent display screen will cause errors in the 3D measured data. After analyzing the refraction light path in the transmissive display dual-screen system, this paper proposes a method of compensating the refraction error caused by the transparent display screen. To start with, we analyze the measurement principle of the transmissive display dual-screen system and the cause of the refraction error. Then, the refraction error introduced by the transparent display screen is compensated through phase in the parameter calibration process. Finally, the proposed method of refraction error compensation is verified on the developed measurement system. The experimental results show that the proposed method eliminates the error caused by the refraction effect and improves the measurement accuracy of 3D mirror object shape.