In the cooling design of gas turbine vane, sheet metal parts were used to arrange the impact cooling holes in the platform and inner cavity, and divided the chamber space for impact cooling. During the service period, due to the impact of temperature load and air flow, the sheet metal parts were prone to bulge, crack, fall off, which worsen the cooling effect. In order to ensure the safe and reliable operation of blade and sheet metal parts, it was necessary to design reasonable sheet metal structure and accurately predict the service life. In this paper, material mechanical property test of GH3536 was carried out to obtain its constitutive equation and fatigue performance parameters. The structure of sheet metal parts were designed, then the temperature field of the blade and the sheet metal was simulated by using the fluid-thermal-solid coupling method, and the stress-strain analysis was carried out by using the elastic-plastic constitutive model. Finally, the fatigue life of the sheet metal was obtained, and the service life meet the design requirements. This work was helpful to prolong the life of sheet metal structure and ensure the cooling effect of blade.