The invention relates to a preparation technique of brominated polyvinyl chloride granules, which comprises the following steps: a. adding a nonpolar organic solvent into polyvinyl chloride to dissolve the polyvinyl chloride to form an organic polyvinyl chloride solution; b. adding a catalyst into the organic polyvinyl chloride solution, meanwhile, heating to 40-60 DEG C, adding simple substance bromine, and stirring to carrying out bromination reaction; c. after the bromination reaction is carried out for 1.5-3.5 hours, adding an alkali solution into the organic polyvinyl chloride solution subjected to bromination to terminate the reaction, and washing with water to a neutral state; and d. putting the neutral organic polyvinyl chloride solution subjected to bromination into a high-speed stirring and drying machine, operating the high-speed stirring and drying machine for 30 minutes, drying the organic polyvinyl chloride solution subjected to bromination, and curing to obtain the brominated polyvinyl chloride granules. The invention overcomes the defects of poor dispersity and high tendency to solvent entrapment in the separation process in the brominated polyvinyl chloride granule preparation technique.