The effects of incident angle on welding performance of fiber laser butt welding of high-strength automobile steel are researched. The ideal parameters obtained by the previous test is used. The 4 kW fiber laser is used to weld the dual-phase high-strength steel B340/590DP with the thickness of 1.6 mm at different incident angles with a butt joint. Then the effects of incident angle on the weld topography, cross section topography, tension and shearing property and micro-structure are analyzed. The results show that good weld topography, fine micro-structure and greater tension and shearing property can be obtained when the laser beam incident angle is less than 40°. When the incident angle is more than 40°, the single-sided weld is obtained on the back of the bead.