Laser powder bed fusion (LPBF) technology offers advantages such as the fabrication of complex structures and integrated forming, indicating great potential for future development. However, the use of LPBF technology to produce nickel-based superalloys, which are highly crack-sensitive, presents a significant challenge. During the LPBF process, the appropriate overlap distance between melt pools is critical for ensuring material density and minimizing crack formation. In this study, Inconel 939 nickel-based superalloys were fabricated via the LPBF technique. The effects of different scanning spacings (50, 70 and 90 μm) on the microstructure and metallurgical defects were investigated, and the crack formation mechanism was elucidated. The results show that with the laser power fixed at 270 W and the scanning speed at 1800 mm/s, the crack density initially decreased and then increased as the hatch distance increased. At a hatch distance of 70 μm, the lowest crack density of 0.27 mm/mm2 is achieved. Therefore, appropriate hatch distances help improve material density and reduce crack formation, whereas larger hatch distances may increase defects and residual stress, thereby raising the risk of cracks.