Space solar cell array is the only power source for satellites, and the mechanical impact on solar array during its in-orbit service will directly affect the normal operation of the satellites. Therefore, it is of great significance to study the stress and strain law of space solar array. In this paper, we establish a strain-testing system for space solar array, and this system can help test the strain data of space solar array under simulated space vacuum and thermal cycling field. We find that the space solar cells suffer compression deformation at high temperature and tensile deformation at low temperature. The total maximum strain of the free cell and pasted cell under the same conditions are 1270 and 1320 με, respectively. In addition, the strain of middle area is 113% higher than that of the edge area in one space solar cell. The rupturing strain of space solar cell is 2080 με. These measured data conduce to studying the deformation characteristics of solar cells in space environment, which can help researchers get the deformation regularity of space solar cells. They also provide experimental basis for stress-relieving arrangement of space solar array. This research provides technical support for studying the deformation resistance of space solar cells.