Abstract: This paper presents the thermal deformation testing of a deployable cable-mesh reflector by using the photogrammetry method with a thermal vacuum facility. The typical thermal conditions are adopted based on the on-orbit thermal analysis of antenna. The target temperatures on different parts of the antenna are reached by using an infrared heating device and the electric heater of the antenna itself at the same time. Testing results show that the RMS value of the reflector’s profile obtained by the thermal deformation modeling analysis agrees well with the measured data under typical thermal conditions, thus the model can be used for accurately predicting the on-orbit thermal deformation of the antenna. Based on that result and the on-orbit thermal environmental analysis results, the thermal deformation of the antenna is calculated for the on-orbit prediction. It is indicated that the maximum RMS value of the reflector is 0.19 mm under the maximum temperature difference condition during orbiting.