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Highlights • Nano- to submicron-sized process provides a way to optimize microstructure of HDDR powders. • The uniform Nd-rich phase distribution could effectively optimize the deformation ability. • The coercivity was increased from 1.18 T to 1.37 T for die-upset magnet with NSG HDDR powders. • The remanence was increased from 1.1 T to 1.25 T for die-upset magnet with NSG HDDR powders. Abstract Nano-crystalline and micron-crystalline Nd-Fe-B powders were employed to hydrogenation-disproportionation-desorption-recombination (HDDR) process to investigate the structural factors of deformation ability in HDDR powders. It was found that the deformation ability and magnetic properties of the final die-upset magnet were optimized significantly by nano-crystalline powders. Structure investigation shows that the variations in coercivity and deformation ability were attributed to the Nd-rich phase distribution in HDDR powders. Meanwhile, enhancement of remanence and squareness indicated the uniform distribution of Nd-rich phase and the narrow grain size distribution by using nano-sized crystalline powders were in favor of c-axis alignment of 2:14:1 phase. [ABSTRACT FROM AUTHOR]