When the galvanized auto-body panel steel sheets were cut by CO₂ laser and the three-dimensional (3D) laser cutting machine,problems such as collision and burn-off are easily generated in the uphill,downhill and corner. So the corresponding improvement measurements are proposed in this paper. Experimental results indicate that to obtain 3D cutting workpiece with good cutting quality,high cutting precision and small hot effect width,the incident angle changed along with the pose of cutting head should be limited less than 20°. The collision can be eliminated by increasing craft spot,adjusting cutting direction and changing incident angle. Burn-off in uphill,downhill and corner can be effectively avoided by decreasing laser power,and opting pulse laser and reducing its duty ratio and using the air to take as auxiliary gas and so on. At the same time,the cutting quality is evaluated from the kerf width,cutting surface roughness,cutting surface ripple and hot affected width.