The magnetic Nd-Fe-B powders were prepared by a thermochemical method, consisting of the processes of spray-drying, debinding, milling, H$_2$-reduction, Ca-reduction, and washing. The optimum process conditions were studied by microstructural and thermal analysis. The resultant Nd-Fe-B powder was spherical with the size of 1 ${mu}{ extrm}{m}$. Effects of the process parameters of each step on the microstructure of the powders were investigated, and their magnetic properties were evaluated.