Digital holography experiment with the off-axis angle supervised accurately is designed to satisfy the requirement of off-axis angle. After introducing one reflector，two beam splitters，supervisin g CCD and calculating the off-axis angle by spatial spectrum analysis，the angle between the reference and the objective beams is supervised online. This setup can not only realize the alternation between the in-axis state and off-axis state without rearrangement，but also can separate the original objective image from the direct term and the twin image when the recorded digital holography is used for reconstruction. It can decrease the demanding of digital holography recording on CCD and make the reconstructing view field used effectively. Resolution target is used as the objects in the experiments carried out. The feasibility and effectiveness of this off-axis angle supervising setup are verified by optical experiments.