The present invention relates to technology of producing superfine aluminium hydroxide and is characterized by the process including three subsequent procedures of using sodium aluminate solution to prepare active crystal seeds, decomposing superfine aluminium hydroxide slurry fluid and separating solid from liquid. The preparabon procedure of super fine crystal seeds from sodium aluminate solution includes diluting and cooling sodium aluminate solution, decomposing and forming aluminium hydroxide gel slurry fluid and the procedure of separating solid from liquid includes separating solid andliquid, adding water and washing and over drying to obtain superfine aluminium hydroxide.