Herein, a planar mirror-assisted single-camera DIC system is proposed, which expands a single-camera DIC system to a four-virtual-camera DIC system. The plane’s mirrored images can perform panoramic imaging on the front and back surfaces of the measured object from different angles, and both optical path systems can perform panoramic imaging on the front and back surfaces of the measured object. The optical path separation allows for 3D stereo measurements, which compensates for the common single-camera DIC system’s ability to only measure in-plane deformation. In the tensile experiment of the metal specimen, the four subregions have similar strain changes, strain is generally distributed at approximately 0.0125, and the displacement precision increases as the tensile value increases; the 3D reconstruction experiment of the decision currency has good 3D stereo reconstruction effect, and there is no obvious difference compared with the traditional four-camera DIC system. The system has a simple structure, meets the requirements for 3D panoramic dynamic deformation measurement, and has a promising future application. Meanwhile, future works will implement the optical path system to better adapt to the needs of various application environments.