Preparation method of brown reactive dye

The invention discloses a preparation method of a brown reactive dye. The preparation method of the brown reactive dye comprises the following steps of: (1) causing aniline-2,5-disulfonic acid, hydrogen chloride and sodium nitrite to react in water so as to obtain a first mixed solution; (2) adding 1-naphthylamine-6-sulfonic acid to the first mixed solution prepared in the step (1) in the coexistence of a naphthyl sulfonate formaldehyde condensate and an amino OE-OP segmented copolymer, and reacting to obtain a second mixed solution; (3) adding hydrogen chloride and sodium nitrite to the second mixed solution prepared in the step (2), and reacting to obtain a third mixed solution; (4) adding 1-naphthylamine-8-sulfonic acid to the third mixed solution prepared in the step (3), and reactingto obtain a fourth mixed solution; (5) adding cyanuric chloride to the fourth mixed solution, and reacting to obtain a fifth mixed solution; and (6) adding ammonia water to the fifth mixed solution, and reacting to obtain bro