The invention relates to the technical field of conducting films of touch screens, and particularly relates to an ITO (Indium Tin Oxide) conducting film for a touch screen and a preparation method thereof. The ITO conducting film comprises a resin matrix of 100-150 micrometers, a first ITO layer of 8-10 nanometers, a second ITO layer of 6-8 nanometers, a third ITO layer of 4-6 nanometers and a fourth ITO layer of 2-4 nanometers, wherein the first ITO layer, the second ITO layer, the third ITO layer and the fourth ITO layer are sequentially deposited on the resin matrix. According to the invention, the resin matrix is heated to 200-240 DEG C every time through four layered deposition and four crystallization processes, and the recrystallization temperature 150 DEG C of the ITO layers is achieved, so that the ITO can be subjected to a crystallization process after being deposited every time, and the perfect crystallization of the ITO layer is effectively promoted; in order to reduce the influence of thickness on the crystallization, the thicknesses of the first ITO layer, the second ITO layer, the third ITO layer and the fourth ITO layer are sequentially reduced. In conclusion, the prepared ITO conducting film for the touch screen has the advantages of high transmittance, low resistivity and good chemical stability.