Abstract: The laser welding seam at the sharp corner tends to be uneven due to the necessarily varying speed profile. To solve this problem, we propose a triangular detour based speed planning strategy for laser welding. When the laser welding torch comes to the corner, the laser is powered off while the torch keeps moving along a triangle with the S-shaped speed profile to eliminate the possible impact to the welding platform. When the torch comes back to the corner, the laser is powered back on while the torch moves at the original welding speed. Consequently, the welding speed is kept constant to guarantee the even welding seam. This speed planning strategy is applicable to various break angles at the corner. The feasibility and effectiveness of the proposed strategy are verified by both simulation and experiment results.