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Frictionstir welding (FSW) technology can be used to reduce weight，improvethe comprehensive performance and save cost，especially itcan weld 2xxx and 7xxx aluminum alloys that can’t be welded by the traditionwelding way, so FSWed integral structure is potential to be one of aeronauticalstructure in the future. Some aircraft parts of dissimilar alloys need to be joinedtogether to be one part. So this paper studied the distribution of residualstress, mechanical properties and fatigue crack growth properties of similarand dissimilar 2024-T3 and 7075-T6 thin friction stir welded plates.Similar and dissimilar 2024-T3 and 7075-T6 plates werewelded by proper friction stir welding parameters. And then X-ray diffractionmethod was used to measure residual stress profiles in welded plates. Residualstress profiles of the similar and dissimilar plates were compared andanalyzed. Finite element models of similar and dissimilar welded plates werebuilt by ABAQUS. The residual stress intensity factor profiles in differentwelded samples were calculated and compared. The effect of residual stress onfatigue parameter was simulated and quantified. Mechanical properties of FSWedjoints and fatigue crack growth were measured. The numerical results werecompared with the experimental ones.