Kapton film will be applied with fiber-reinforced composites in the ITER toroidal field coil insulation system by use of its strong dielectric strength and the excellent balance of thermal, mechanical, physical and chemical properties. In order to assess the influence of Kapton film on the mechanical properties of the insulation system, three testing procedures (static tension, short-beam shear and double-lap shear) and numerical calculation were used to investigate the tensile and shear strength of the insulation material with or without Kapton film. It shows that the numerical results are in close agreement with the experimental values for different testing procedures.