Abstract:  This article conducts an integrated study on laser groove processing, cutting, cleaning, and welding of 20mm thick Q355B steel. There are currently many studies on laser cutting and cleaning parameters, but there is relatively little research on the influence of laser cleaning on the mechanical properties of ultra-high power cutting thick plate sections and subsequent welding joints. This study uses a single platform fiber laser cutting machine to cut the plate, and uses a specific welding platform for welding. Through methods such as 3D contour measurement instrument, tensile test, impact test, etc., the effects of laser cutting and cleaning on surface morphology, roughness, and welding joint performance are analyzed. The results indicate that integrated processing of high-power lasers can shorten the processing cycle and improve efficiency; Laser cleaning can reduce cross-sectional roughness, but has little effect on the performance of welded joints. After cutting Q355B plate with a 20kw laser, laser cleaning is not required, which can reduce the process and improve efficiency. The study provides theoretical reference for efficient processing and welding process optimization of Q355B carbon steel.