The microstructures and fracture morphologies at the fracture position of electron beam welding and near isothermally forged TC11/Ti-22Al-25Nb dual alloy simulation disc underwent thermal exposure at 550℃ and 600℃ for 300 h, 500h respectively, were investigated through tensile and stress-rupture experiments and observed by SEM and TEM. The results indicate that: after the thermal exposure of the samples at room temperature tensile, fracture at the weld position. After 550℃ thermal exposure, the fracture of tensile samples belong to ductile fracture while tensile samples belong to brittle cleavage fracture when it experienced 600 ℃ thermal exposure, and crack source always starts in surface of the sample. As the thermal exposure temperature increasing and time extend, an overall improvement in room temperature tensile strength, ductility decreases, lasting time is reduced, and the element of the welding connection area distributes more uniform, the composition curve becomes more smooth.