The invention discloses a gamimycin injection and a preparation method thereof. The gamimycin injection is composed of gamimycin, vitamin C and water for injection, wherein every 100ml of the solution contains 5-35 g of gamimycin , vitamin C 1~10g, all the other are water for injection; Gamithromycin injection of the present invention uses vitamin C to improve the dissolving speed of gamimycin bulk drug, has increased the solubility of gamimycin bulk drug, and vitamin C not only It has a good solubilizing effect, and also has anti-oxidation effect, which can improve the stability of the product; the gamimycin injection of the present invention is a weakly acidic aqueous phase injection, which can be used in compatibility with most drugs, greatly increasing the Gamithromycin has stable properties after long-term storage, has little irritation to the injection site, fast absorption, remarkable effect, high safety, simple prescription, convenient quality control of raw and auxiliary materials, cost saving, and is suitable for industrial production.