Abstract:The one-step aging behavior of 7A52 aluminum alloy laser welding joint were characterized by mechanical properties, electrical conductivity test, EDS and TEM. It was found that the base metal and the weld joint of 7A52 aluminum alloy need almost same time to reach peak hardness under different temperatures. When the aging temperature was increased from 120℃ to 160℃, The age hardening rate of contact joint was noticeably accelerated and the time to reach peak hardness was significantly reduced. After aging 16h at 140℃, the tensile strength of joint, loss of weight and the conductivity were 351 MPa, 0.0070 g/min and 21.2 MS/m. Compared with the data after aging 24h at 120℃, the result shows 1.13% tensile strength of joint decrease, 2.94% loss of weight decrease and 12.2% conductivity increase. Thus aging 24h at 120℃ is considered as a reasonable one-step aging process. The precipitate phase of the welding joint and the base metal was MgZn2. At 140℃, the precipitate phase got an amount increase and coarsening with the aging time extending. And the main strengthening phase were η， phase (MgZn2) and GP zone at peak aging state.