Abstract: The Nd-Fe-B SC acts as a precursor for NdFeB permanent magnets, and its microstructure plays a significant role in influencing the magnetic properties of the final magnet. This study utilized SEM, EDS, XRD, and HELOS to characterize the microstructure of the Nd-Fe-B SC. A relationship between the thickness of the Nd-Fe-B SC and its microstructural characteristics was established. The magnetic properties of the magnetic powder were assessed using a VSM. The findings indicate that none of the Nd-Fe-B SC, regardless of their thickness, contained the α-Fe phase. As the thickness of the castings increased, the width of the columnar crystals also grew. Secondary dendrites appeared when the casting thickness reached 0.30 mm or more. For the 0.30 mm thick casting, the orientation of the main phase near the roller surface was found to be optimal, with an I(006)/I(105) ratio of 20.67. Compa-risons of performance showed that, as the thickness increased, coercivity decreased monotonically, while saturation magnetisation first increased and then decreased. The magnetic powder in the 0.30 mm thick casting exhibited the highest saturation magnetisation.