High purity nano HNS was prepared by the combination of solution quench recrystallization and solvent-antisolvent recrystallization. Results show that crystal appearance of nano HNS is smoother with particle size from 58.9 nm to 231.6 nm, and its purity is increased from 90.1% to 99.44%, the BET specific surface area is determined to be 19.27 m²·g^-1. Sensitivity tests for the raw HNS and nano HNS indicate that nano HNS is less sensitive to impact than raw HNS, but more sensitive to short impulse shock waves.