This study proposes a method for the overall measurement of small deformations based on multi-camera three-dimensional digital image correlation (3D-DIC) to achieve flexible and high-precision measurement of deformations in multiple key regions of complex satellite structures. A binocular 3D-DIC subsystem is established for obtaining high-precision deformation fields in each key area. Combined with the beam adjustment optimization and the 3D reconstruction method of the same name point, the external calibration of the pose of the subsystem is completed. The measured data of the subsystem is spliced according to the calibration parameters, and the global deformation field is obtained. Under laboratory conditions, the overall deformation field and measurement error of multiple installation surfaces are measured in the thermal deformation experiment of the satellite honeycomb structure. The results show that the overall displacement measurement error of the method for the system is 0.96 μm±0.45 μm/m. The method meets the measurement requirements of a high-precision and flexible measurement range. Also, it has good applicability to overlapping and discrete fields of view and provides a reliable measurement method for monitoring the satellite structure’s stability in space.