The present invention discloses a preparation technics for 2-amino-3,6,8-naphthalenesulfonic acid, which solves the problem of the large volume of wasted water drained by the technics in the prior art, and decreases the individual cost of the raw material of 2-naphthol, thereby decreasing the cost. The fabrication technics includes that 2-naphthol is sulfonated in sulphuric acid or oleum to produce 6,8-naphthalin-disulfuric acid (G acid), 3,7- naphthalin-disulfuric acid (R acid), and the other sulfuric acid derivatives of 2-naphtalins, then potassium sulphuric is added for crystallization to obtain 6,8-naphthalin-potassium disulfuric (G salt), the stock solution undergoes high-temperature hydrolysis, in which 3,7- naphthalin-disulfuric acid (R acid) and the other sulfuric acid derivatives of 2-naphtalins are hydrolyzed into 2-naphthalin, then the stock liquid is extracted, oxidized, decolored and condensed to retrieve the potassium sulphuric, which is recycled to procedure involved in the production of 6,8-naphthalin-potassium disulfuric (G salt), which undergoes ammonolysis and sulfonation to produce 2-amino-3,6,8-naphthalintrisulfuric acid.