Aluminium-lithium alloy is the ideal material in aerospace industry for its lightweight and high strength. 2 mm aluminium-lithium alloy is used for laser cutting by employing 1 kW fiber laser to improve its cutting quality. The effect of the process parameters on the quality of laser cutting, such as defocus, gas pressure, laser power and cutting speed is studied. Cutting qualities under continuous laser mode and pulsed laser mode are compared. The results reveal that pulsed laser mode can achieve a better cutting quality. Optimization of technological parameters is performed by using the visual analysis of orthogonal experiment, the analysis of variance and the analysis of signal to noise ratio. Finally, the good quality with 0.087 mm slag thickness and 4.81 μm surface roughness can be obtained.