DP590 dual-phase steel and 6016 aluminum alloy were used as test materials. A laser deep fusion welding test was conducted using Ti powder in the lap mode of "steel at the top and aluminum at the bottom," and the microstructure and properties of the joint before and after adding the Ti powder between them were compared. The test results show that under a laser power of 1600 W, a welding speed of 35 mm/s, a defocus amount of +1.0 mm, and back protection using the Ar protective gas of 15 L/min, the welding quality is improved by the addition of the Ti powder, and the average line load is 110 N/mm, which is 10% higher than the condition without the addition of the powder. The addition of the Ti powder can refine the grain size. During the welding process, the Ti powder will be absorbed into the liquid aluminum and react with Fe to form a ductile phase Fe₂Ti, which will improve the property of weld-joint.