The effect of preparation temperature and polymer additive on superfine HNS particles was studied to investigate its microstructure. The results show that superfine HNS particles disperse well drying 48 h at 22-25 ℃,and aggregates drying 2 h at 100 ℃. The pore volume and specific surface area of HNS-Ⅳ adsorbed 8 h in vacuum at 25 ℃ are larger than that of HNS-Ⅳ adsorbed 2 h in vacuum at 65 ℃. The surface area is not totally depended on mean particle size but linearly changes with pore volume to some extent. The mean particle size of pure HNS-Ⅳ is 0.789 μm,the pore volume and surface area are 0.032 cm³?g^-1 and 15.13 m²?g^-1 respectively. The mean particle size,pore volume and surface area of particles containing 3% polymer are 0.594 μm,0.026 cm³?g^-1 and 11.41 m²?g^-1 respectively. The mean particle size,pore volume and surface area of particles containing 4% polymer respectively are 0.594 μm,0.026 cm³?g^-1 and 11.41 m²?g^-1 respectively.