The processing techniques including output current, scanning speed, defocusing distance, auxiliary gas species and pressure, which influence the quality of the flow curve, have been studied with the NdYAG lasers. The cutting quality is measured by the kerf width, surface roughness of the incision and slag quantity. The best processing parameters have been gained with the analyses and experiments. The high quality flow curve has been cut with the output current of 175 A, pulse width of 0.3 ms, pulse frequency of 70 Hz, scanning speed of 40 mm/s, defocusing distance of 0 and oxygen gas pressure of 1.0 MPa.