Abstract: This study investigates the effects of pulse frequency, width, and voltage on the microstructure and mechanical properties of M170P/DC06 differential thickness welded joints using an SW-500 Nd: YAG pulsed laser. Results indicate that the DC06 thin plate HAZ exhibits coarse blocky ferrite, while the M170P thick plate HAZ consists of fine ferrite and granular bainite. Optimal hardness (200 HV) is achieved at 20 Hz pulse frequency and 300 mm/min welding speed, with a gradient decrease from thick to thin plate.