The humic acid with average particle size of 60 nm was prepared by alkali-solution and acid-isolation and high shearing technology using weathered coal as raw material.The optimum condition to prepare nanoscale humic acid was obtained through orthogonal experiment：reaction temperature 60℃，reaction time 150 min，ammonia concentration 25%(mass)，solid-to-liquid ratio 1∶10，and addition amount of crystalization adjusting agent 0.15% of the total reaction solution.The size distribution，chemical structure，crystallization properties，morphology，specific surface area of nanometer humic acid were characterized by laser particle size analyzer，FTIR，GPC

XRD，SEM，and specific surface area analyzer(BET).The results showed that the particle size of the sample was well distributed，meanwhile，the sample had good dispersion，the average particle size was 60 nm，specific surface area was 110.31 m2·g-1

and relative molecular weight was 119.Double bonds in the structure，specific surface area and functional groups increased obviously.