In order to get fine stability of the optical reflector of space remote sensor under the lunar-based environment of force and thermal constraints, base on the inclement environment of force and thermal constraints where lunar-based extreme ultraviolet camera is under, a reflector subassembly meeting lunar-based environment is designed. The finite element analysis of the reflector subassembly show that the first resonant frequency of the reflector subassembly is 354 Hz, the RMS value is 3.62 nm and 2.46 nm under 1 g gravity and ΔT=50℃ temperature change, the result shows the surface accuracy of reflector meets the needs of imaging quality. At last, through the statics surface accuracy detection, mechanical testing temperature tolerance test and imaging resolution test, the result shows RMS value is less than 14nm and meets the design require. It demonstrates that the reflector subassembly structure is reasonable.