In three-dimensional vision measurements, single-camera mirror binocular stereo vision systems composed of a camera and mirrors have become popular, owing to their high flexibility and compactness. However, the calibration of these systems is different from traditional two-camera stereo vision systems, because there is no rigid-body transformation between the actual camera and the virtual camera. A calibration method for single-camera mirror binocular vision system is proposed, which can establish the rigid-body transformation by rotating the image based on the sole principal point. The comparative experiments showed that the proposed method yielded a higher accuracy than the traditional method.