The invention relates to a gastric cancer targeted recombinant toxin and a preparation method thereof, and belongs to a targeted recombinant toxin and a preparation method thereof. The gastric cancer targeted recombinant toxin is formed by connecting human gastrin G17 with recombinant toxin PE38KDEL derived from pseudomonas exotoxin A, and particularly the recombinant toxin is prepared by using G17 expressed by a prokaryotic expression system and translated reversely as a guiding unit through gene engineering expression; and a unique fermentation condition for producing a soluble protein in a large scale is established, and the recombinant toxin targeting gastric cancer and having high selective killing activity is provided.