The invention relates to an LHRH (luteinizing hormone-releasing hormone antagonist) lyophilized powder injection with improved stability. The preparation mainly comprises cetrorelix as an active ingredient, an excipient, a pH regulator, an antioxidant and a local analgesic agent, wherein the addition of the antioxidant can improve the stability of the preparation, and the addition of the local analgesic agent can relieve the pains of patients while having no impact on the active ingredient. The preparation process of the preparation mainly comprises weighing, dissolving, adsorbing pyrogen with activated carbon, filtering, final filtering, subpackaging, vacuum drying, plugging, and covering. The LHRH lyophilized powder injection provided by the invention can control the stimulatory function of an ovary, prevent early release of immature ovarian follicles, and help become pregnant. The LHRH lyophilized powder injection has the advantages of stable quality, definite therapeutic effect, and good patient compliance.