The present invention relates to a method of preparing a transformed Cucumis melo using Acrobacterium tumefaciens, more particularly, to a method for preparing a transformed Cucumis melo, which comprises the steps of: (a) inoculating a cotyledon from Cucumis melo with Agrobacterium tumefaciens harboring a suitable vector; (b) regenerating the inoculated cotyledon in a regeneration medium containing 3.0-8.0 mg/l of kinetin as growth regulator and 0.5-3.0 mg/l of IAA (Indole-3-acetic acid) and culturing the inoculated cotyledon to obtain regenerated shoots; and (c) culturing the regenerated shoots on a rooting medium to obtain the transformed Cucumis melo.