To reduce the uncertainty region of a three-dimensional (3D) position, a four-camera 3D digital image correlation (3D-DIC) system was built by orthogonally arranging two sets of two-camera DIC systems. The theoretical model proposed herein revealed the relationship between 3D coordinates and system parameters and the propagation of the matching error to the position error. Numerical simulation and experiment were conducted to verify the theory. The simulation and experimental results indicated that the 3D position error of the four-camera system was smaller than that of the two-camera DIC system. The present contribution proves the feasibility of using four-camera DIC systems to improve measurement accuracy.