To accurately recommend the amount of mulberry seeds used in nursery, the standard of technical parameters was formed. The single seed morphological structure (such as length, width, maximum projection area, aspect ratio, area coefficient, single grain weight, single grain thickness, single grain volume, single grain density, 1000-grain weight) and the characteristics of seed accumulations (seed bulk density, seed specific gravity, seed density and seed porosity) of ‘Panzhihua 1’ (a resource domesticated species of Morus macroura) were studied by a comparison with seeds of ‘Jisang 3’ (a resource domesticated species of Morus alba). The results show that: (1) the testa of ‘Panzhihua 1’ is bright brown, with surface coat and short stipe; the testa of ‘Jisang 3’ is dark brown, smooth and hairless, with long stipe; although the seeds of both species are pentahedral, ‘Jisang 3’ is more flat, and ‘Panzhihua 1’ is more three-dimensional; (2) the length, width, maximum projection area, length width ratio, area coefficient, single seed volume and 1000 seed weight of ‘Panzhihua 1’ are smaller than those of ‘Jisang 3’, only 45.21%, 69.04%, 53.06%, 68.71%, 93.20%, 26.94% and 32.86% of those of ‘Jisang 3’, respectively; (3) the seed bulk density, seed proportion and seed porosity of ‘Panzhihua 1’ are 58.88%, 51.25% and 85.26% of those of ‘Jisang 3’ respectively; (4) the recommended seed quality and volume of ‘Panzhihua 1’ are 1.35 kg/hm2 and 5.55 L/hm2, respectively. The results could provide a basis for the seedling, and production and storage of the seeds of Morus macroura.