The invention relates to: a composition for culturing natural killer cells, comprising, as an active ingredient, a fusion protein comprising an IL-2 protein and a CD80 protein; and a method for preparing natural killer cells by using same. Particularly, a composition for culturing natural killer cells, comprising, as an active ingredient, a fusion protein comprising IL-2 or a variant thereof and CD80 or a fragment thereof, of the present invention, promotes the proliferation of natural killer cells, induces the expression of CD16 and NKp46, and increases the expression and secretion of granzyme B and perforin, thereby being effectively usable in the preparation of natural killer cells having an excellent anticancer immune function.
