A cross-loop slot frequency selection element is developed on the surface of three- dimensional hemispherical shell by laser processing. Advantages of laser processing compared with other processing methods and the influence of laser processing parameters on the machining quality of the cross-loop slot frequency selection element are discussed. Firstly, processing method of the frequency selection element of the spherical surface is analyzed, processing defects in laser processing are introduced, and the parametric characterization is put forward according to the characteristics of the defects. Then, single factor experiments are carried out on the experimental parts, the change rules of the processing quality of the cutting unit are analyzed, and the reasonable parameter range is obtained. Finally, parametric tests are carried out according to the reasonable parameter range, and the improvement effect of the machining quality is discussed as well. Experimental results indicate that the galvanometer laser processing speed is 15 times higher than that of ordinary computer numerical control machining system, and the processing defects account for 5% or less in control.