The invention discloses a multi-time water process crystallization method of thiamine hydrochloride. The method comprises the following steps: heating and stirring crude thiamine hydrochloride and purified water until the crude thiamine hydrochloride is dissolved, naturally cooling the obtained solution, cooling the naturally cooled solution with ice water, carrying out heat insulation crystallization, filtering the solution to obtain a filtrate I and filter residues I, and washing the filter residues I with ethanol to obtain thiamine hydrochloride; concentrating the filtrate I, stirring the filtrate I to naturally cool the filtrate I, cooling the naturally cooled filtrate I with ice water, carrying out heat insulation crystallization, and filtering the cooled filtrate I to obtain a filtrate II and filter residues II, and washing the filter residues II with ethanol to obtain thiamine hydrochloride; and concentrating the filtrate II, stirring the filtrate II to naturally cool the filtrate II, cooling the naturally cooled filtrate II with ice water, carrying out heat insulation crystallization, filtering the cooled filtrate II to obtain a filtrate III and filter residues III, and washing the filter residues III with ethanol to obtain the thiamine hydrochloride. Multi-time water process crystallization is adopted to substitute alcohol process crystallization, so the yield of the thiamine hydrochloride is improved, and the natural bulk density of the thiamine hydrochloride is increased to 0.56 g/mL from 0.20 g/mL. The method greatly increases the natural bulk density of the thiamine hydrochloride.