The invention discloses a fasudil hydrochloride injection and a preparation method thereof. The fasudil hydrochloride injection is composed of a raw material of hydroxyfasudil and auxiliary materials of hydrochloric acid, edetate disodium, disodium hydrogen phosphate, methionine, activated carbon for injection and water for injection. The fasudil hydrochloride injection comprises, by weight, 30 parts of the hydroxyfasudil, a hydrochloric acid solution with concentration being 1 mol/L, 0.1-0.4 part of the edetate disodium, 0.1-0.3 part of the disodium hydrogen phosphate, 0.15-0.25 part of the methionine, appropriate amount of the activated carbon for injection and 1500-2500 parts of the water for injection; and pH of the hydrochloric acid solution with the concentration being 1 mol/L when used for adjusting the full dose of the recipe water for injection is 4.0-5.0, and the fasudil hydrochloride injection is a novel and efficient vasodilator agent. The preparation method for the fasudil hydrochloride injection is simple, and the used auxiliary materials have been used for a long period, so that safety is guaranteed, cost is low, and the fasudil hydrochloride injection is convenient for industrial production.