In response to the problem of laser cutting processing being unable to blow in special environments, an experimental study was conducted on the impact of 10000 watt level laser loop path, cutting movement speed, focal length, and cutting seam width on the cutting quality of 20 mm thick 20CrNiMo steel under no blowing conditions based on the self-developed 10 000 watt level laser cutting experimental platform. In addition, the optimization relationship between laser power and cutting movement speed were systematically analyzed to obtain better cutting results. The research results indicate that for a 10 000 W power laser, the optimal process parameters are the top-down loop path, cutting movement speed range is 2528mm/s, focal length 0 mm, and cutting seam width 25 mm. For laser powers of 6 000 W, 7 000 W, 8 000 W, 9 000 W, 10 000 W, and 12 000 W, the corresponding optimal cutting movement speeds were 5 mm/s, 5 mm/s, 10 mm/s, 15 mm/s, 25 mm/s, and 25 mm/s, respectively. The research results contribute to providing reference for the research and application of ultra-high power laser in the field of medium and thick steel under non blowing conditions