The invention discloses a preparation method of an amino pyridine bromide compound, relating to the field of organic synthesis. The amino pyridine bromide compound takes pyridine bromide formamide as raw material, and is prepared according to the following formula of Hofmann degradation reaction which comprising the following steps of: (1) dropping liquid bromine into alkali liquid with the concentration of 2.0-4.0 mol/L at -5-0 DEG C, reacting for 1.0 hour to obtain sodium hypobromite or potassium hypobromite, wherein the alkali is sodium hydroxide, potassium hydroxide or sodium methoxide; (2) adding the pyridine bromide formamide with the general foumula I to the hypobromite solution at room temperature for dissolving, raising temperature to 50-80 DEG C, reacting for 0.5-2 hours, decreasing temperature to 0 DEG C for separating out solids, and filtrating to obtain crude products; extracting the filtrate with an organic solvent, removing the solvent, and merging the crude products; re-crystallizing by using petroleum ether, and drying to obtain amino pyridine bromide. Wherein, the mole ratio of the general formula I to the alkali is 1:4-8, the mole ratio of the general formula I to water is 1:80-160, and the mole ratio of the general formula I to the liquid bromine is 1:1-2; and the organic solvent is dichloromethane, chloroform or normal hexane. The invention has the advantages of one-step reaction, simple process, low requirement on equipment, and high product purity, and the yield coefficient is around 50 percent.