A 10 kW fiber laser was used to perform laser cutting process experiments on 10 mm thick 2A12 aluminum alloy. The effects of cutting speed, auxiliary air pressure, defocus amount, nozzle diameter, and nozzle height on cutting quality were systematically studied. During the study, the cutting quality was evaluated on the basis of the striation morphology and the height of dross. Firstly, through the single-factor experiments, the optimal parameter interval of the defocus amount, the nozzle diameter, and the nozzle height was determined. Then, full-factor experiments were performed. The results showed that there is a cutting speed interval that can obtain good cutting quality under a certain auxiliary air pressure, and increasing the auxiliary pressure to a certain extent will increase the speed interval.For 10 mm thick aluminum alloy laser cutting, the best process parameters are obtained: laser power 9 kW, cutting speed 1 750 mm/min, auxiliary air pressure 20 Bar, nozzle diameter 3.0 mm, nozzle height 0.8 mm, defocus amount -7 mm. The analysis of the recast layer of the laser cutting section shows that the precipitated phases become continuous distribution at the grain boundaries and diffuse distribution within the grains, which will have a strong hindrance to the movement of dislocations and improve the resistance to crack initiation on the surface of the material to a certain extent.