The effects of chemical composition and deformation temperature on the magnetic properties of hot-deformed Nd-Fe-B magnets were studied systematically, with the following results: 1) all magnet samples consisted of single- and multi-domain grains, 2) single-domain grains increased with decreasing crystal grain sizes, and 3) both coercivity and its temperature coefficient were strongly related to crystal grain size and total rare earth content. By optimizing the chemical composition and the hot-deformation conditions, Dy-free magnets with a coercivity of 1600 kA/m, which is 23% higher than that of conventional magnets, were fabricated.