Abstract: The thermal stress of metallic film/composite material substrate structure for satellite antenna reflector during high-low temperature cycle is analyzed and simulated in this paper.Samples after high-low temperature cycle was observe and analyzed by microscope,and the mechanism of microcrack formation in the metallic films is also described.An appropriate material was used for forming a stress-releasing layer between metal film and composite material substrate;which intends to release the breaking stress generated by epoxy resin in this layer.Experiment result conformed that the buffer layer has effectively restrained the formation of micro cracks in the metallic.A further method for restrain the forming of microcracks in metallic film is suggested.