Abstract: Fatigue test was carried out for MIG welded joint and laser -MIG composite welded joint of 6A01 aluminum alloy profile, and the fatigue properties of the two welded joints were compared and studied. The results show that the median fatigue strength of the laser -MIG composite welded joint samples with and without reinforcement is 93.38, 108.57 MPa, respectively, which is higher than that of MIG welded joint samples with and without reinforcement. The laser -MIG composite welded joint has narrower fusion zone and finer grain structure, which reduces the rate of fatigue crack initiation and crack propagation, and has better fatigue performance than the MIG welded joint. Surface stress concentration position, subsurface pores, porosity and other defects of the MIG welded joint are sensitive parts of fatigue crack initiation, which greatly reduces fatigue crack initiation life. Decreasing surface stress concentration and welding defects of aluminum alloy welded joint is the key to improve the fatigue performance.