The invention relates to the field of medicine, in particular to a tropisetron hydrochloride injection and a preparation method thereof. The injection is prepared from the following constituents in parts by weight: 1.13-28.2 parts of tropisetron hydrochloride, 3-75 parts of sodium acetate, 1.7-42.5 parts of glacial acetic acid, 1.2-30 parts of sodium chloride, and 3000-6000 parts of water for injection. The preparation method comprises the following steps: (1) weighing tropisetron hydrochloride, adding the weighed tropisetron hydrochloride into the water for injection, which accounts for 60-95% of the total prescription dosage, adding sodium acetate, glacial acetic acid and sodium chloride to the water, stirring to enable the substances to be dissolved, adding activated carbon for needle, stirring and using a titanium bar to coarsely filtering out and removing carbon; (2) adding the rest water for injection, and sequentially using microfiltration membranes of 0.60-0.45 microns and 0.45-0.10 microns to filter the solution. The tropisetron hydrochloride injection provided by the invention is a colorless clear liquid, high in clarity, good in solubility, low in impurities, free of adverse effects, and convenient and safe to use.