The invention discloses an N(2)-L-alanyl-L-glutamine preparation for injection and a preparation method thereof. The preparation is prepared through directly preparing a liquid with a raw material N(2)-L-alanyl-L-glutamine, freeze-drying, and carrying out separate packing. The method comprises the following steps: (1) taking the raw material N(2)-L-alanyl-L-glutamine, adding water for injection, and fully stirring to completely dissolve N(2)-L-alanyl-L-glutamine; (2) adding needle active carbon to a solution obtained in step (1), fully stirring, filtering to decarburize, and carrying out germ filtering through passing through a filter with a diameter of 0.2 [mu]m; (3) putting a filtrate obtained in step 2 into a sterilized freeze-dried disc, loading the disc into a cooling chamber of a freeze dryer, and carrying out pre-freezing, vacuumizing, heating, sublimation drying, desorption drying, and vacuum break to end freeze-drying; and (4) accessing high purity nitrogen for drying and degerming, taking out of the chamber, carrying out asepsis packing, tamponading, and capping. So N(2)-L-alanyl-L-glutamine for injection is obtained.