The invention relates to a method for preparing aniline-2-sulfonic acid, in particular to a method for preparing aniline-2-sulfonic acid through aniline catalysis and sulfonation. With metal hydrogen sulfate serving as a catalyst, aniline is directly catalyzed and sulfonated to prepare aniline-2-sulfonic acid in a transposition mode. According to the method, aniline is directly catalyzed and sulfonated to prepare aniline-2-sulfonic acid in the transposition mode, so that aniline-2-sulfonic acid is prepared from aniline through a one-step method, and the total yield of aniline-2-sulfonic acid reaches 95% or above; the process route is short, the quantity of the three wastes is small, and the cost is low.