The invention relates to a calcitriol injection and a preparation method thereof. The injection is prepared from the following ingredients in percentage by weight: 0.0005% of calcitriol, 1.2-1.6% of meglumine, 18-24% of polyethylene glycol 400, 1.2-1.7% of polyethylene glycol 6000, 0.1% of antioxidant, an appropriate amount of isotonicity regulator and the balance of water for injection. According to the injection, the content of calcitriol is remarkably increased, so that the drug dosage is reduced; and the stability of calcitriol to light and air is improved, and the bioavailability of calcitriol is also remarkably improved.