Abstract: Films are widely used in spacecrafts, but their mechanical properties would degrade in space irradiation environment. This paper reviews the applications of films in spacecraft and the effects of far ultraviolet irradiation on the mechanical properties of Kapton/Al film. It is shown that the tensile strength and the rupture elongation of Kapton/Al film decrease with the increase of the tensile deformation rate and the far ultraviolet irradiation. The far ultraviolet irradiation will cause the rupture and cross linkage of molecular bonds in the film, deoxidation of C―CO, denitrification of C―N. The increase of C―H percentage attributes mainly to the mechanical property degradation of Kapton/Al film under far ultraviolet irradiation.