The invention discloses a cefpiramide sodium powder injection and a preparation method thereof. The preparation method comprises the following steps: dissolving cefpiramide sodium powder and sodium benzoate in water for injection; dropwisely adding sodium bicarbonate water solution or hydrochloric acid water solution to regulate the pH value to 6.2-7.2; filtering; and freeze-drying the filtrate to obtain the cefpiramide sodium powder injection. In the invention, cefpiramide sodium powder and sodium benzoate are directly dissolved in water for injection to prepare the powder injection in a slightly acid or neutral environment. Thus, the invention has the advantages of controllable related substances, cost saving, simple technical process and energy saving, and is applicable to industrial production.