<p>This study systematically investigates the effect of process parameters of laser powder bed fusion (LPBF) on the forming quality of polycrystalline γ-TiAl alloy at microscopic level through molecular dynamics (MD) simulation. By changing the laser power (152–320 µW) and scanning speed (0.2-1 Å/ps), the effects of different parameters on the evolution of the forming process and the microstructure of crystallization were elucidated. The results indicate that increasing the laser power and decreasing the scanning speed both increase the temperature peak width and prolong the duration of the molten pool, which promotes the diffusion of powder particle atoms. However, both high power and low scanning speed increase the total energy input of the molten pool, promoting the accumulation of heat. Ultimately, this leads to a higher proportion of HCP structures in the powder bed. Furthermore, lower scanning speed and laser power both result in higher crystallinity, with scanning speed having a more remarkable regulatory influence on the crystallinity. Grain analysis indicates that with the increase of laser power and the decrease of scanning speed, the grain width of the formed alloy gradually increases, and the grains transform from fine equiaxed crystals or short columnar crystals to coarse long columnar crystals. Tensile testing reveals that both laser power and scanning speed present a nonlinear relationship on the tensile strength of TiAl alloy, which is the result of the combined action of factors such as grain size, dislocations and residual stress. During stretching, the FCC and HCP structures of the stretching block undergo mutual transformation, and the dislocation entanglement at the grain boundaries formed by laser forming could impede slip, thereby enhancing the tensile strength.</p> Graphical Abstract <p></p>