Sintered and aged Dy-doped NdFeB magnets was studied in this work. The magnetic properties, microstructures and compositions was investigated by hysteresis loop instrument, thermal field emission scanning electron microscopy and energy disperse spectroscopy, respectively. The result of analysis indicated that Dy element mainly distributed in the Nd-rich phase, Nd-Dy oxides and Dy-rich particles which is located at the grain boundary of the sintered magnets, in addition to the main crystal phase Nd2Fe14B. The optimized aging process is beneficial to promote a reasonable diffusion and distribution for Dy element. The Dy contents of Nd-riched phases, Nd-Dy oxide, and Dy-riched particle decreased successively in the sintered, the high temperature aged and the optimal two-stage aged Dy-doped NdFeB permanent magnets. The measurements demonstrated that the enhancement of the coercivity of the aged Dy-doped NdFeB Magnet was caused mainly by the Dy element reasonable distribution.