Abstract—This paper presents an experimental study on the effects of the process parameters on laser cutting of 3 mm thick mild steel plates. The parameters investigated includes laser power, gas pressure and cutting speed. The kerf width and the cut edge roughness are examined. The laser source used is a continuous wave CO2 laser with maximum power of 4 kW. The obtained results show that as the laser power increases, the average kerf width increases. Oxygen gas pressure also has a remarkable effect on the cut edge roughness. It is found that as the gas pressure increases, the roughness is increased. Increasing of the cutting speed gives the narrower average kerf width and the smoother cut surface.