Primer applicable to security door and preparation method of primer

The invention relates to a primer applicable to a security door and a preparation method of the primer. The primer is prepared from the following raw materials in percentage by weight: base stocks: 30%-50% of aqueous epoxy ester resin and 6%-10% of amino resin; aids: 3%-5% of a cosolvent, 1%-3% of a neutralizer, 10%-15% of deionized water, 0.5%-2% of a wetting dispersant, 0.1%-0.5% of a defoaming agent and 0.1%-0.3% of a base material wetting agent; pigments and fillers: 15%-25% of a red pigment free of heavy metal, 5%-10% of compound zinc phosphate, 5%-10% of compound ferrotitanium powder and 1%-5% of nanoscale precipitated barium sulphate. According to the preparation method, an aqueous coating is used as a solvent, so that the fire risk during construction is eliminated, the atmospheric pollution is alleviated, and the working environment condition is improved; a coating process of existing security doors is not changed, the workability of the product is relatively good, and the aqueous coating can be used for direct coating construction in humid environment on a wet surface and is well adaptive to the surface of the material; a coating tool can be washed by water, so that the consumption of a cleaning solvent is greatly reduced.