In order to study the ablation quality process of carbon fiber reinforced plastics(CFRP) with 20 W nanosecond laser, theoretical analysis and experimental verification were carried out by the single-factor experimental method and photo-section method. Effects of scanning speed, peak power, and defocus amount on the surface processing quality of the material were studied. A piece of 0.5 mm thick CFRP was ablated in experiments. The results show that adjusting the defocusing amount made the focus of the laser and the material plane at the same horizontal height, which could minimize the scanning line width, reduce the heat-affected zone and improve the laser energy utilization. When the laser scanning speed is 220 mm/s and, the peak laser power is 10 W, the average surface roughness of CFRP composite is the smallest. About 3.50 μm, and the roughness data stability sample difference is the best, about 0.133 μm2; the laser process parameter combination method ablation CFRP composite materials can obtain ideal processing performance. The above research for pulsed laser processing CFRP material process research provides some references and lays a certain practical foundation for the application of pulsed laser processing composite material process.