The invention discloses a hot galvanizing tool and a preparation method thereof. The substrate of the tool is carbon steel and is coated with an anti-corrosion alloy coating which is 70-120 microns and contains Si and Mo, wherein Si and Mo exist in a form of Fe3Si+Fe3Mo+MoSi2 alloy and the Si content and the Mo content of the anti-corrosion alloy coating are 5-16% and 2-10% respectively. The preparation method of the hot galvanizing tool comprises the steps of processing tools, preparing a penetrating agent, canning, carrying out heat treatment and the like. According to the preparation method, the surface of carbon steel substrate is modified through Si-Mo co-penetrated heat treatment process so that the anti-corrosion alloy coating with high chemical stability and high hardness can be formed on the surface of the substrate. The anti-corrosion alloy coating is capable of improving the corrosion resistance of steel in a liquid zinc corrosive medium and also capable of improving the high-temperature oxidation resistance of steel and enhancing the wear resistance of the surface of steel, thereby greatly prolonging the service life of the hot galvanizing tool.